Solid-state imaging device, imaging apparatus, substrate, semiconductor device and method of manufacturing the solid-state imaging device

ABSTRACT

A solid-state imaging device is a solid-state imaging device in which a first substrate formed on a first semiconductor wafer and a second substrate formed on a second semiconductor wafer are bonded via connect that electrically connects the substrates, wherein the first substrate includes photoelectric conversion units, the second substrate includes an output circuit that acquires a signal generated by the photoelectric conversion unit via the connector and outputs the signal, and dummy connectors that support the first and second bonded substrates are further arranged in a substrate region in which the connectors are not arranged in a substrate region of at least one of the first substrate and the second substrate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a solid-state imaging device, animaging apparatus, and a method for manufacturing the solid-stateimaging device. Further, the present invention relates to a substrateand, more specifically, a substrate having a number of electrodes formedto protrude on a base, and a semiconductor device using the substrate.

Priority is claimed on Japanese Patent Application No. 2012-006986,filed on Jan. 17, 2012, Japanese Patent Application No. 2012-079215,filed on Mar. 30, 2012, and Japanese Patent Application No. 2012-081930,filed on Mar. 30, 2012, the content of which is incorporated herein byreferences.

2. Description of Related Art

In recent years, video cameras, electronic still cameras, and the likehave been widely popularized. A CCD (Charge Coupled Device)-type oramplification-type solid-state imaging device is used for such a camera.The amplification-type solid-state imaging device guides signal chargesgenerated and accumulated by a photoelectric conversion unit of a pixelon which light is incident to an amplification unit provided in thepixel, and outputs the signal amplified by the amplification unit fromthe pixel. In the amplification-type solid-state imaging device, aplurality of pixels are arranged in a two-dimensional matrix. An exampleof the amplification-type solid-state imaging device includes a CMOS(Complementary Metal Oxide Semiconductor)-type solid-state imagingdevice using CMOS transistors.

In related art, a general CMOS-type solid-state imaging device adopts ascheme of sequentially reading, for each row, signal charges generatedby photoelectric conversion units of the respective pixels arranged in atwo-dimensional matrix. In this scheme, since a timing of exposure inthe photoelectric conversion unit of each pixel is determined by startand end of readout of signal charges, the exposure timing differs foreach row.

Further, uses of a CMOS-type solid-state imaging device having a globalshutter function are increasing. In the CMOS-type solid-state imagingdevice having the global shutter function, signal charges generated byphotoelectric conversion units are normally accumulated until readout isperformed. For this reason, it is necessary to have accumulationcapacitors having a light shielding property. In such a CMOS solid-stateimaging device of the related art, all pixels are simultaneouslyexposed, and then signal charges generated by respective photoelectricconversion units are simultaneously transferred to the respectiveaccumulation capacitors in all the pixels and temporarily accumulated.The signal charges are sequentially converted into pixel signals andread at a predetermined readout timing.

A solid-state imaging device in which a MOS image sensor chip in whichmicropads are formed on the side of a wiring layer in each unit cell anda signal processing chip in which micropads are formed on the side ofthe wiring layer in positions corresponding to the micropads of the MOSimage sensor chip are connected by microbumps is disclosed in JapanesePatent Laid-Open Publication No. 2006-49361. Further, a method ofpreventing an increase in a chip area using a solid-state imaging devicein which a first substrate having photoelectric conversion units formedtherein and a second substrate having a plurality of MOS transistorsformed therein are bonded is disclosed in Japanese Patent Laid-OpenPublication No. 2010-219339.

A semiconductor device having a three-dimensional structure hasattracted attention as a powerful structure to avoid various barriersfaced by a semiconductor device having a two-dimensional structure, suchas limits of lithography technology in miniaturization, an increase inwiring resistance or parasitic effects due to miniaturized wirings andan increased wiring length, a saturation tendency of an operating speedassociated with the increase, or a high electric field effect due tominiaturized element dimensions, and to maintain an improved degree ofintegration, by three-dimensionally integrating a semiconductor elementwith a structure in which a number of semiconductor active layers arestacked.

For manufacture of the semiconductor device having a three-dimensionalstructure, a stacked semiconductor device formed by bonding wafershaving a number of very small electrodes formed therein has beenstudied.

In such a stacked semiconductor device, formation of protrusionelectrodes of a conductive material and dummy protrusion units having agreater height than the protrusion electrodes (hereinafter referred toas “dummy electrodes”) on wafers and definition of a gap between thewafers using the projection units is disclosed in Japanese PatentLaid-Open Publication No. 2007-281393. Accordingly, a predetermined gapis accurately held by an electrical insulating material attached to asurface of an electronic part in an inner region of the protrusion unit.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, a solid-stateimaging device is a solid-state imaging device in which a firstsubstrate formed on a first semiconductor wafer and a second substrateformed on a second semiconductor wafer are bonded via connector thatelectrically connects the substrates. The first substrate includesphotoelectric conversion units. The second substrate includes an outputcircuit that acquires a signal generated by the photoelectric conversionunit via the connector and outputs the signal. Dummy connectors thatsupport the first and second substrates that are bonded with each otherare further arranged in a substrate region in which the connector is notarranged, in a substrate region of at least one of the first substrateand the second substrate.

According to a second aspect of the present invention, in thesolid-state imaging device according to the first aspect, an arrangementinterval of the dummy connectors may be the same as an arrangementinterval of the connector.

According to a third aspect of the present invention, in the solid-stateimaging device according to the second aspect, an arrangement of atleast one of the dummy connectors may be omitted.

According to a fourth aspect of the present invention, in thesolid-state imaging device according to the third aspect, thearrangement of the dummy connector may be omitted to reduce pressure tobe applied to the first semiconductor wafer and the second semiconductorwafer at the time of the bonding.

According to a fifth aspect of the present invention, in the solid-stateimaging device according to the second aspect, an arrangement positionof at least one of the dummy connectors may be shifted from arrangementpositions at equal intervals.

According to a sixth aspect of the present invention, in the solid-stateimaging device according to the fifth aspect, when dicing is performedafter the first semiconductor wafer and the second semiconductor waferare bonded, arrangement positions of the dummy connectors may be shiftedfrom arrangement positions at equal intervals so that the firstsemiconductor wafer and the second semiconductor wafer are notseparated.

According to a seventh aspect of the present invention, the solid-stateimaging device according to the second aspect may include a plurality ofphotoelectric conversion elements as the photoelectric conversion units,the photoelectric conversion elements may be classified into one of oneor more groups, and a plurality of photoelectric conversion elementsclassified into the same group may share one connector.

According to an eighth aspect of the present invention, in thesolid-state imaging device according to the first aspect, thearrangement interval of the dummy connectors may be the same as anarrangement interval of the photoelectric conversion units.

According to a ninth aspect of the present invention, in the solid-stateimaging device according to the eighth aspect, an arrangement of atleast one of the dummy connectors may be omitted.

According to a tenth aspect of the present invention, in the solid-stateimaging device according to the eighth aspect, an arrangement positionof at least one of the dummy connectors may be shifted from arrangementpositions at equal intervals.

According to an eleventh aspect of the present invention, in thesolid-state imaging device according to the first aspect, the dummyconnectors may be arranged to prevent distortion, cracks, and chippingof the first substrate and the second substrate.

According to a twelfth aspect of the present invention, in thesolid-state imaging device according to the first aspect, an arrangementinterval of at least some of the dummy connectors may be greater thanthe arrangement interval of the photoelectric conversion units.

According to a thirteenth aspect of the present invention, in thesolid-state imaging device according to the first aspect, thearrangement interval of at least some of the dummy connectors may begreater than the arrangement interval of the connectors.

According to a fourteenth aspect of the present invention, in thesolid-state imaging device according to any one of the first tothirteenth aspects, a plurality of unit circuits may be arranged in aperipheral circuit region different from a region in which thephotoelectric conversion units are arranged, and an arrangement positionof the dummy connector arranged on a circuit element constituting theunit circuit may be common to the plurality of unit circuits.

According to a fifteenth aspect of the present invention, in thesolid-state imaging device according to any one of the first tothirteenth aspects, a plurality of unit circuits may be arranged in aperipheral circuit region different from a region in which thephotoelectric conversion units are arranged, and the dummy connector maybe arranged to suppress variations in circuit characteristics of theplurality of unit circuits.

According to a sixteenth aspect of the present invention, in thesolid-state imaging device according to the first aspect, the firstsubstrate may include a peripheral circuit, and the dummy connectionportions may be arranged in a region outside the peripheral circuitincluded in the first substrate.

According to a seventeenth aspect of the present invention, in thesolid-state imaging device according to the first aspect, the secondsubstrate may include a peripheral circuit, and the dummy connectors maybe arranged in a region outside the peripheral circuit included in thesecond substrate.

According to a eighteenth aspect of the present invention, in thesolid-state imaging device according to the first aspect, the firstsubstrate and the second substrate may include a peripheral circuit, andthe dummy connectors may be arranged in regions outside the peripheralcircuit included in the first substrate and outside the peripheralcircuit included in the second substrate.

According to a nineteenth aspect of the present invention, in thesolid-state imaging device according to the first aspect, the secondsubstrate may include an accumulation circuit that accumulates a signalacquired via the connector, and the output circuit may output the signalaccumulated in the accumulation circuit.

According to a twentieth aspect of the present invention, a solid-stateimaging device is a solid-state imaging device in which a firstsubstrate formed on a first semiconductor wafer and a second substrateformed on a second semiconductor wafer are bonded via connector thatelectrically connects the substrates. The first substrate includesphotoelectric conversion units. The second substrate includes an outputcircuit that acquires a signal generated by the photoelectric conversionunit via the connector and outputs the signal. Dummy connectors that donot electrically connect the first substrate with the second substrateare further arranged in a region in which the connectors are notarranged, in a substrate region of at least one of the first substrateand the second substrate.

According to a twenty-first aspect of the present invention, an imagingapparatus is an imaging apparatus in which a first substrate formed on afirst semiconductor wafer and a second substrate formed on a secondsemiconductor wafer are bonded via connectors that electrically connectthe substrates. The first substrate includes photoelectric conversionunits. The second substrate includes an output circuit that acquires asignal generated by the photoelectric conversion unit via the connector,and outputs the signal. Dummy connectors that support the first andsecond substrates that are bonded with each other are further arrangedin a substrate region in which the connectors are not arranged, in asubstrate region of at least one of the first substrate and the secondsubstrate.

According to a twenty-second aspect of the present invention, a methodof manufacturing a solid-state imaging device is a method ofmanufacturing a solid-state imaging device in which a first substrateformed on a first semiconductor wafer and a second substrate formed on asecond semiconductor wafer are bonded via connector that electricallyconnects the substrates. The method includes further arranging dummyconnectors that support the first and second substrates are bonded, in asubstrate region in which the connectors are not arranged in a substrateregion of at least one of the first substrate including photoelectricconversion units and the second substrate including an output circuitthat acquires a signal generated by the photoelectric conversion unitvia the connector and outputs the signal.

According to a twenty-third aspect of the present invention, thesolid-state imaging device according to the first or second aspect maybe diced to remove at least some of the dummy connectors.

According to a twenty-fourth aspect of the present invention, in thesolid-state imaging device according to the first or second aspect, aground wiring may be provided in the first substrate, and the groundwiring may be connected to the dummy connector.

According to a twenty-fifth aspect of the present invention, in thesolid-state imaging device according to the first or second aspect, aground wiring may be provided in the second substrate, and the groundwiring may be connected to the dummy connector.

According to a twenty-sixth aspect of the present invention, in thesolid-state imaging device according to the first or second aspect, afirst ground wiring may be provided in the first substrate, a secondground wiring may be provided in the second substrate, and the firstground wiring and the second ground wiring may be connected to the dummyconnector.

According to a twenty-seventh aspect of the present invention, in thesolid-state imaging device according to the twenty-third aspect, heatconduction patterns insulated from the photoelectric conversion unit andconnected to the dummy connectors may be provided in the firstsubstrate, and the solid-state imaging device may be diced to remove atleast some of the heat conduction patterns.

According to a twenty-eighth aspect of the present invention, in thesolid-state imaging device according to the twenty-third aspect, heatconduction patterns insulated from the output circuit and connected tothe dummy connector may be provided in the second substrate, and thesolid-state imaging device may be diced to remove at least some of theheat conduction patterns.

According to a twenty-ninth aspect of the present invention, in thesolid-state imaging device according to the twenty-third aspect, a firstwiring insulated from the photoelectric conversion unit and connected tothe dummy connector may be provided in the first substrate, a secondwiring insulated from the output circuit and connected to the dummyconnector may be provided in the second substrate, and the solid-stateimaging device may be diced to remove at least some of the heatconduction patterns.

According to a thirtieth aspect of the present invention, the method ofmanufacturing a solid-state imaging device according to thetwenty-second aspect may include a removal process of performing dicingto remove at least some of the dummy connectors after the connectorarranging process.

According to a thirty-first aspect of the present invention, in themethod of manufacturing a solid-state imaging device according to thetwenty-second aspect, a ground wiring may be provided in the firstsubstrate, and the dummy connection portion may be connected to theground wiring in the connector arranging process.

According to a thirty-second aspect of the present invention, asubstrate includes a base having a predetermined thickness; a wiringprovided in the base; an electrode provided in one surface in athickness direction of the base and including a plurality of circuitelectrodes connected to the wiring; and a dummy region provided in thesame surface as the electrode and including a plurality of dummyelectrodes not connected to the wiring. In at least a portion of thedummy region, the dummy electrodes are arranged as a dummy electrode setin which a plurality of dummy electrodes are arranged at a predetermineddummy pitch and the maximum distance between the dummy electrodes iswithin a predetermined value.

According to a thirty-third aspect of the present invention, in thesubstrate according to a thirty-second aspect, a set pitch that is apitch at which the dummy electrode sets are arranged may be set to begreater than the dummy pitch.

According to a thirty-fourth aspect of the present invention, in thesubstrate according to a thirty-second or thirty-third aspect, at leastone of a diameter of the circuit electrode and a formation pitch may beset to be equal to or less than 20 micrometers.

According to a thirty-fifth aspect of the present invention, in thesubstrate according to any one of a thirty-second to thirty-fourthaspects, a height of the dummy electrode may be equal to or less thanthe height of the circuit electrode.

According to a thirty-sixth aspect of the present invention, in thesubstrate according to any one of thirty-second to thirty-fifth aspects,the set pitch may be at least 10 times the dummy pitch.

According to a thirty-seventh aspect of the present invention, in thesubstrate according to any one of thirty-second to thirty-fifth aspects,the set pitch may be at least 3 times the maximum distance between thedummy electrodes.

According to a thirty-eighth aspect of the present invention, asemiconductor device is a semiconductor device formed by bonding atleast two substrates having an electrode formed therein, wherein atleast one of the substrates is a substrate according to any one ofthirty-second to thirty-seventh aspects.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a configuration of an imagingapparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of an imagingunit included in the imaging apparatus according to the first embodimentof the present invention.

FIG. 3A is a cross-sectional view of the imaging unit included in theimaging apparatus according to the first embodiment of the presentinvention.

FIG. 3B is a plan view of the imaging unit included in the imagingapparatus according to the first embodiment of the present invention.

FIG. 4 is a circuit diagram illustrating a circuit configuration of apixel included in the imaging apparatus according to the firstembodiment of the present invention.

FIG. 5 is a circuit diagram illustrating a circuit configuration of apixel included in the imaging apparatus according to the firstembodiment of the present invention.

FIG. 6A is a reference diagram illustrating a state in which pixels areclassified into a plurality of groups in the imaging apparatus accordingto the first embodiment of the present invention.

FIG. 6B is a reference diagram illustrating a state in which pixels areclassified into a plurality of groups in the imaging apparatus accordingto the first embodiment of the present invention.

FIG. 7 is a timing chart illustrating an operation of a pixel includedin the imaging apparatus according to the first embodiment of thepresent invention.

FIG. 8 is a timing chart illustrating an operation of a pixel includedin the imaging apparatus according to the first embodiment of thepresent invention.

FIG. 9 is a timing chart illustrating the operation of a pixel includedin the imaging device according to the first embodiment of the presentinvention.

FIG. 10 is a schematic diagram illustrating an arrangement example ofconnection portions included in the imaging apparatus according to thefirst embodiment of the present invention.

FIG. 11A is a schematic view illustrating a planar structure and across-sectional structure of a substrate in which a first substrate anda second substrate are bonded according to the first embodiment of thepresent invention.

FIG. 11B is a schematic view illustrating a planar structure and across-sectional structure of a substrate in which a first substrate anda second substrate are bonded according to the first embodiment of thepresent invention.

FIG. 12 is a schematic view illustrating a planar structure of asubstrate in which a first substrate and a second substrate are bondedaccording to the first embodiment of the present invention.

FIG. 13 is a schematic diagram illustrating an arrangement of column ADCcircuits according to a second embodiment of the present invention.

FIG. 14 is a schematic diagram illustrating an arrangement pattern ofdummy connector arranged in a peripheral circuit region according to thesecond embodiment of the present invention.

FIG. 15 is a schematic diagram illustrating an arrangement pattern ofdummy connector arranged in a peripheral circuit region according to thesecond embodiment of the present invention.

FIG. 16 is a schematic view illustrating a planar structure of asubstrate in which a first substrate and a second substrate are bondedaccording to a third embodiment of the present invention.

FIG. 17 is a schematic view illustrating a planar structure of asubstrate in which a first substrate and a second substrate are bondedaccording to the third embodiment of the present invention.

FIG. 18 is a schematic view illustrating a planar structure of asubstrate in which a first substrate and a second substrate are bondedaccording to the third embodiment of the present invention.

FIG. 19 is a cross-sectional view of primary portions of a substrate inwhich a first substrate and a second substrate are bonded according to afourth embodiment of the present invention.

FIG. 20 is a cross-sectional view of primary portions of a substrate inwhich a first substrate and a second substrate are bonded according to afifth embodiment of the present invention.

FIG. 21 is a schematic view illustrating a planar structure of asubstrate in which a first substrate and a second substrate are bondedaccording to the fifth embodiment of the present invention.

FIG. 22 is a plan view illustrating, on an upper side, a substrateaccording to an embodiment of the present invention and a diagramillustrating, on a lower side, an operation in which the substrate isbonded.

FIG. 23 is an enlarged view illustrating a unit region of the substrate.

FIG. 24 is an enlarged view illustrating a boundary between an electrodeand a dummy region in the unit region.

FIG. 25A is a view illustrating a difference of an effect of stress dueto an arrangement of a dummy electrode.

FIG. 25B is a view illustrating a difference of an effect of stress dueto an arrangement of dummy electrodes.

FIG. 25C is a view illustrating a difference of an effect of stress dueto an arrangement of dummy electrodes.

FIG. 26 is a cross-sectional view illustrating an example of a regionnear a boundary after the substrate is bonded.

FIG. 27A is a view illustrating a process of singulation.

FIG. 27B is a perspective view illustrating one unit region cut as asemiconductor device.

FIG. 28 is a plan view illustrating a dummy electrode set of a variantof the present invention.

FIG. 29 is a cross-sectional view illustrating another example of aregion near a boundary after the substrate of the present invention isbonded.

DETAILED DESCRIPTION OF THE INVENTION First Embodiment

Hereinafter, a first embodiment of the present invention will bedescribed with reference to the drawings. The following descriptionincludes specific detailed contents as an example. However, thoseskilled in the art should, of course, understand that, even when thedetailed contents are varied or modified, the variations andmodifications are within the scope of the present invention.Accordingly, various embodiments to be described below will be describedwithout loss of generality of the present invention described in theclaims and without limitation on the present invention.

FIG. 1 illustrates a configuration of an imaging apparatus according tothe present embodiment. The imaging apparatus according to one aspect ofthe present invention may be an electronic device having an imagingfunction or may be a digital video camera, an endoscope or the like, aswell as a digital still camera.

The imaging apparatus illustrated in FIG. 1 includes a lens 201, animaging unit 202, an image processing unit 203, a display unit 204, adriving control unit 205, a lens control unit 206, a camera control unit207, and a camera manipulation unit 208. While a memory card 209 is alsoillustrated in FIG. 1, the memory card 209 may not be a component uniqueto the imaging device by causing the memory card 209 to be detachablewith respect to the imaging device.

While respective blocks illustrated in FIG. 1 may be realized by variousparts, such as electrical circuit parts such as a CPU, a memory and thelike of a computer, an optical part such as a lens, and a manipulationpart such as a button or a switch from a point of view of hardware, andmay be realized by a computer program or the like from a point of viewof software, the blocks are drawn as functional blocks realized bycooperation of the hardware and the software. Accordingly, it isunderstood by those skilled in the art that the functional blocks may berealized in various forms by a combination of hardware and software.

The lens 201 is an imaging lens for forming an optical image of asubject on an imaging surface of the imaging unit 202 constituting asolid-state imaging device (solid-state imaging element). The imagingunit 202 includes a plurality of pixels, and converts the optical imageof the subject formed by the lens 201 into a digital image signalthrough photoelectric conversion and outputs the digital image signal.The image processing unit 203 performs various digital image processingon the image signal output from the imaging unit 202.

The display unit 204 displays an image based on the image signalsubjected to the image processing for display by the image processingunit 203. This display unit 204 can reproduce and display a still imageand perform video (live view) display to display an image within animaging range in real time. The driving control unit 205 controls anoperation of the imaging unit 202 based on an instruction from thecamera control unit 207. Based on an instruction from the camera controlunit 207, the lens control unit 206 controls the aperture and the focalposition of the lens 201.

The camera control unit 207 controls the entire imaging apparatus. Anoperation of the camera control unit 207 is defined by a program storedin a ROM built in the imaging apparatus. The camera control unit 207reads this program and performs various controls according to contentdefined by the program. The camera manipulation unit 208 includesvarious manipulation members for a user to perform various manipulationinputs for the imaging apparatus, and outputs a signal based on a resultof the manipulation input to the camera control unit 207. Concreteexamples of the camera manipulation unit 208 may include a power switchfor turning power of the imaging apparatus on and off, a release buttonfor instructing still image photography, and a still image photographymode switch for switching a still image capturing mode between a singlephotography mode and a continuous photography mode. The memory card 209is a recording medium for holding an image signal processed forrecording by the image processing unit 203.

FIG. 2 illustrates a configuration of the imaging unit 202. The imagingunit 202 includes a pixel unit 2 including a plurality of pixels 1, avertical scanning circuit 3, a column processing circuit 4, a horizontalreadout circuit 5, an output amplifier (an output circuit) 6, and acontrol circuit 7. Arrangement positions of the respective circuitelements illustrated in FIG. 2 do not necessarily match actualarrangement positions.

In the pixel unit 2, the plurality of pixels 1 are arranged in atwo-dimensional matrix. In FIG. 2, 120 pixels 1 are arranged in 10rows×12 columns. However, an array of the pixels illustrated in FIG. 2is an example, and the numbers of rows and columns may be 2 or more.Further, FIG. 2 is a diagram schematically illustrating a state in whichthe respective pixels 1 are arranged in a matrix shape. The respectivepixels are not arranged separately as illustrated in FIG. 2. As will bedescribed below, some circuit elements are shared among the plurality ofpixels in practice.

In the present embodiment, while a region including all the pixels,included in the imaging unit 202, is a pixel signal readout targetregion, a portion of the region including all the pixels, included inthe imaging unit 202, may be a readout target region. It is desirablefor the readout target region to include at least all pixels in aneffective pixel region. Further, the readout target region may includeoptical black pixels (constantly light-shielded pixels) arranged outsidethe effective pixel region. A pixel signal read from the optical blackpixel is used, for example, for correction of a dark current component.

The vertical scanning circuit 3 includes, for example, a shift registerand performs driving control of the pixels 1 in units of rows. Thisdriving control includes a reset operation, an accumulation operation,and a signal readout operation of the pixels 1. In order to perform thisdriving control, the vertical scanning circuit 3 outputs a controlsignal (a control pulse) to each pixel 1 via a control signal line 8provided in each row and independently controls the pixel 1 for eachrow. As the vertical scanning circuit 3 performs the driving control, apixel signal is output from the pixel 1 to a vertical signal line 9provided in each column.

The column processing circuit 4 is connected to the vertical signal line9 of each column, and performs signal processing such as noise removaland amplification on the pixel signal output from the pixel 1. Thehorizontal readout circuit 5 includes, for example, a shift register.The horizontal readout circuit 5 selects a pixel column to read pixelsignals, and sequentially selects the column processing circuit 4according to the selected pixel column. Further, the horizontal readoutcircuit 5 reads the pixel signals by sequentially outputting the pixelsignals from the column processing circuit 4 to the horizontal signalline 10. The output amplifier 6 performs signal processing on the pixelsignal output to the horizontal signal line 10. The output amplifier 6outputs the pixel signal to the outside via an output terminal 11. Thecontrol circuit 7 generates a clock signal serving as a reference for anoperation of the vertical scanning circuit 3, the column processingcircuit 4, the horizontal readout circuit 5 and the like, a controlsignal or the like, and outputs the signal to the vertical scanningcircuit 3, the column processing circuit 4, the horizontal readoutcircuit 5, and the like.

FIGS. 3A and 3B illustrate a cross-sectional structure (FIG. 3A) and aplanar structure (FIG. 3B) of the imaging unit 202. In an exampleillustrated in FIGS. 3A and 3B, a dummy connection unit is notdescribed. The dummy connection will be described below. The imagingunit 202 has a structure in which two substrates (a first substrate 20and a second substrate 21) having circuit elements (photoelectricconversion elements (photoelectric conversion units), transistors,capacitors, etc.) constituting the pixels 1 arranged therein overlap.The circuit elements constituting the pixels 1 are distributed andarranged in the first substrate 20 (the first substrate) and the secondsubstrate 21 (the second substrate). The first substrate 20 and thesecond substrate 21 are electrically connected so that electricalsignals can be transferred between the two substrates at the time ofdriving the pixels 1. For example, the photoelectric conversion elementsare arranged in the first substrate 20, and the output amplifier 6 thatoutputs a signal output from the photoelectric conversion element to theoutside is arranged in the second substrate 21.

Among two main surfaces of the first substrate 20 (surfaces whosesurface area is relatively greater than a side), the photoelectricconversion elements are formed in the main surface irradiated with lightL and the light radiated to the first substrate 20 is incident on thephotoelectric conversion elements. A number of micropads 22, which areelectrodes for connection with the second substrate 21, are formed inthe main surface opposite to the main surface irradiated with the lightL among the two main surfaces of the first substrate 20. One micropad 22is arranged for one pixel or for a plurality of pixels. Further, amongtwo main surfaces of the second substrate 21, a number of micropads 23,which are electrodes for connection with the first substrate 20, areformed in positions corresponding to the micropads 22 in the mainsurface facing the first substrate 20.

Microbumps 24 are formed between the micropads 22 and the micropads 23.The first substrate 20 and the second substrate 21 are arranged tooverlap so that the micropads 22 and micropads 23 face each other. Themicropad 22 and the micropad 23 are integrally formed to be electricallyconnected by the microbumps 24. The micropad 22, the microbump 24, andthe micropad 23 constitute a connector connecting the first substrate 20and the second substrate 21. The micropads 22 and 23 and the microbump24 have conductivity, and are formed of a metal such as gold or silverhaving high thermal conductivity. The signal based on the signal chargesgenerated by the photoelectric conversion element arranged in the firstsubstrate 20 is output to the second substrate 21 via the micropad 22,the microbump 24, and the micropad 23.

Micropads 25 having the same structure as the micropads 22 are formed ina peripheral portion of the main surface opposite to the main surfaceirradiated with the light L among the two main surfaces of the firstsubstrate 20. Micropads 26 having the same structure as the micropads 23are formed in positions corresponding to the micropads 25 in the mainsurface facing the first substrate 20 among the two main surfaces of thesecond substrate 21. Microbumps 27 are formed between the micropads 25and the micropads 26. A supply voltage for driving the circuit elementsarranged in the first substrate 20 or the circuit elements arranged inthe second substrate 21 is supplied from the first substrate 20 to thesecond substrate 21 or from the second substrate 21 to the firstsubstrate 20 via the micropads 25, the microbumps 27, and the micropads26.

Pads 28 used as an interface with a system other than the firstsubstrate 20 and the second substrate 21 are formed in a peripheralportion of one of the two main surfaces of the second substrate 21.Through electrodes passing through the second substrate 21 may beprovided and used as electrodes for connection with the outside, inplace of the pads 28. In the example illustrated in FIG. 3, while themain surfaces of the first substrate 20 and the second substrate 21 havedifferent areas, the main surfaces of the first substrate 20 and thesecond substrate 21 may have the same areas. Further, the micropadsprovided in the surface of the first substrate 20 may be directly bondedwith the micropads provided in the surface of the second substrate 21 toconnect the first substrate 20 and the second substrate 21, instead ofproviding the microbumps.

The circuit elements constituting the pixels 1 are distributed andarranged in the first substrate 20 and the second substrate 21. Thevertical scanning circuit 3, the column processing circuit 4, thehorizontal readout circuit 5, the output amplifier 6 and the controlcircuit 7 other than the pixels 1 may be arranged in any one of thefirst substrate 20 and the second substrate 21. Further, the circuitelements constituting each of the vertical scanning circuit 3, thecolumn processing circuit 4, the horizontal readout circuit 5, theoutput amplifier 6, and the control circuit 7 may be distributed andarranged in the first substrate 20 and the second substrate 21.Configurations other than the pixels 1 may require transfer of signalsbetween the first substrate 20 and the second substrate 21. However, thefirst substrate 20 and the second substrate 21 may be connected usingmicropads and microbumps or the first substrate 20 and the secondsubstrate 21 may be connected by directly connecting the micropads, asin the pixels 1.

FIG. 4 illustrates a circuit configuration of the pixels 1 correspondingto two pixels. The pixels 1 (two pixels) include photoelectricconversion elements (photoelectric conversion units) 101 a and 101 b,transfer transistors 102 a and 102 b, an FD (floating diffusion) 103, anFD reset transistor 104, a first amplification transistor 105, a currentsource 106, a clamp capacitor 107, sample transistors 108 a and 108 b,analog-memory reset transistors 109 a and 109 b, analog memories 110 aand 110 b, second amplification transistors 111 a and 111 b, andselection transistors 112 a and 112 b. An arrangement position of eachcircuit element illustrated in FIG. 4 does not necessarily match anactual arrangement position.

In FIG. 4, the circuit elements of a first pixel and the circuitelements of a second pixel are included. The first pixel includes thephotoelectric conversion element 101 a, the transfer transistor 102 a,the FD 103, the FD reset transistor 104, the first amplificationtransistor 105, the current source 106, the clamp capacitor 107, thesample transistor 108 a, the analog-memory reset transistor 109 a, theanalog memory 110 a, the second amplification transistor 111 a, and theselection transistor 112 a. The second pixel includes the photoelectricconversion element 101 b, the transfer transistor 102 b, the FD 103, theFD reset transistor 104, the first amplification transistor 105, thecurrent source 106, the clamp capacitor 107, the sample transistor 108b, the analog-memory reset transistor 109 b, the analog memory 110 b,the second amplification transistor 111 b, and the selection transistor112 b. The FD 103, the FD reset transistor 104, the first amplificationtransistor 105, the current source 106, and the clamp capacitor 107,which are arranged in a shared region Sh illustrated in FIG. 4, areshared by the first pixel and the second pixel.

One terminal of the photoelectric conversion element 101 a is grounded.A drain terminal of the transfer transistor 102 a is connected to theother terminal of the photoelectric conversion element 101 a. A gateterminal of the transfer transistor 102 a is connected to the verticalscanning circuit 3 and supplied with a transfer pulse ΦTX1.

One terminal of the photoelectric conversion element 101 b is grounded.A drain terminal of the transfer transistor 102 b is connected to theother terminal of the photoelectric conversion element 101 b. A gateterminal of the transfer transistor 102 b is connected to the verticalscanning circuit 3 and supplied with a transfer pulse ΦTX2.

One terminal of the FD 103 is connected to source terminals of thetransfer transistors 102 a and 102 b, and the other terminal of the FD103 is grounded. A drain terminal of the FD reset transistor 104 isconnected to a supply voltage VDD. A source terminal of the FD resettransistor 104 is connected to the source terminals of the transfertransistors 102 a and 102 b. A gate terminal of the FD reset transistor104 is connected to the vertical scanning circuit 3 and supplied with anFD reset pulse (MST.

A drain terminal of the first amplification transistor 105 is connectedto the supply voltage VDD. A gate terminal that is an input unit of thefirst amplification transistor 105 is connected to the source terminalsof the transfer transistors 102 a and 102 b. One terminal of the currentsource 106 is connected to a source terminal of the first amplificationtransistor 105, and the other terminal of the current source 106 isgrounded. As an example, the current source 106 may include a transistorhaving a drain terminal connected to the source terminal of the firstamplification transistor 105, a grounded source terminal, and a gateterminal connected to the vertical scanning circuit 3.

One terminal of the clamp capacitor 107 is connected to the sourceterminal of the first amplification transistor 105 and the one terminalof the current source 106.

A drain terminal of the sample transistor 108 a is connected to theother terminal of the clamp capacitor 107. A gate terminal of the sampletransistor 108 a is connected to the vertical scanning circuit 3 andsupplied with a sample pulse ΦSH1.

A drain terminal of the sample transistor 108 b is connected to theother terminal of the clamp capacitor 107. A gate terminal of the sampletransistor 108 b is connected to the vertical scanning circuit 3 andsupplied with a sample pulse ΦSH2.

A drain terminal of the analog-memory reset transistor 109 a isconnected to the supply voltage VDD. A source terminal of theanalog-memory reset transistor 109 a is connected to a source terminalof the sample transistor 108 a. A gate terminal of the analog-memoryreset transistor 109 a is connected to the vertical scanning circuit 3and supplied with a clamp and memory reset pulse ΦCL1.

A drain terminal of the analog-memory reset transistor 109 b isconnected to the supply voltage VDD. A source terminal of theanalog-memory reset transistor 109 b is connected to a source terminalof the sample transistor 108 b. A gate terminal of the analog-memoryreset transistor 109 b is connected to the vertical scanning circuit 3and supplied with a clamp and memory reset pulse ΦCL2.

One terminal of the analog memory 110 a is connected to the sourceterminal of the sample transistor 108 a, and the other terminal of theanalog memory 110 a is grounded. A drain terminal of the secondamplification transistor 111 a is connected to the supply voltage VDD. Agate terminal that constitutes an input unit of the second amplifiertransistor 111 a is connected to the source terminal of the sampletransistor 108 a.

A drain terminal of the selection transistor 112 a is connected to asource terminal of the second amplification transistor 111 a. A sourceterminal of the selection transistor 112 a is connected to the verticalsignal line 9. A gate terminal of the selection transistor 112 a isconnected to the vertical scanning circuit 3 and supplied with aselection pulse ΦSEL1.

One terminal of the analog memory 110 b is connected to the sourceterminal of the sample transistor 108 b, and the other terminal of theanalog memory 110 b is grounded. A drain terminal of the secondamplification transistor 111 b is connected to the supply voltage VDD. Agate terminal constituting an input unit of the second amplificationtransistor 111 b is connected to the source terminal of the sampletransistor 108 b.

A drain terminal of the selection transistor 112 b is connected to thesource terminal of the second amplification transistor 111 b. A sourceterminal of the selection transistor 112 b is connected to the verticalsignal line 9. A gate terminal of the selection transistor 112 b isconnected to the vertical scanning circuit 3 and supplied with aselection pulse ΦSEL2. The above-described transistors may havepolarities that are reverse to the above, and the source and drainterminals may be the reverse to those.

The photoelectric conversion elements 101 a and 101 b are, for example,photodiodes, generate (produced) signal charges based on incident light,and hold and accumulate the generated (produced) signal charges. Thetransfer transistors 102 a and 102 b are transistors that transfer thesignal charges accumulated in the photoelectric conversion elements 101a and 101 b to the FD 103. On/off of the transfer transistor 102 a iscontrolled by the transfer pulse ΦTX1 from the vertical scanning circuit3. On/off of the transfer transistor 102 b is controlled by the transferpulse ΦTX2 from the vertical scanning circuit 3. The FD 103 is acapacitor that temporarily holds and accumulates the signal chargestransferred from photoelectric conversion elements 101 a and 101 b.

The FD reset transistor 104 is a transistor that resets the FD 103.On/off of the FD reset transistor 104 is controlled by the FD resetpulse ΦRST from the vertical scanning circuit 3. The photoelectricconversion elements 101 a and 101 b may be reset by simultaneouslyturning the FD reset transistor 104 and the transfer transistors 102 aand 102 b on. The reset of the FD 103/the photoelectric conversionelements 101 a and 101 b controls an amount of charges accumulated inthe FD 103/the photoelectric conversion elements 101 a and 101 b to seta state (a potential) of the FD 103/the photoelectric conversionelements 101 a and 101 b to a reference state (a reference potential ora reset level).

The first amplification transistor 105 is a transistor that outputs,from the source terminal, an amplified signal obtained by amplifying asignal based on the signal charges accumulated in the FD 103, which isinput to the gate terminal. The current source 106 functions as a loadof the first amplification transistor 105 and supplies a current to thefirst amplification transistor 105 to drive the first amplificationtransistor 105. The first amplification transistor 105 and the currentsource 106 constitute a source follower circuit.

The clamp capacitor 107 is a capacitor that clamps (fixes) a voltagelevel of the amplified signal that is output from the firstamplification transistor 105. The sample transistors 108 a and 108 b aretransistors that sample and hold the voltage level of the other terminalof the clamp capacitor 107 and accumulate the signal in the analogmemories 110 a and 110 b. On/off of the sample transistor 108 a iscontrolled by the sample pulse ΦSH1 from the vertical scanning circuit3. On/off of the sample transistor 108 b is controlled by the samplepulse ΦSH2 from the vertical scanning circuit 3.

The analog-memory reset transistors 109 a and 109 b are transistors thatreset the analog memories 110 a and 110 b. On/off of the analog-memoryreset transistors 109 a and 109 b is controlled by the clamp and memoryreset pulses ΦCL1 and ΦCL2 from the vertical scanning circuit 3. Resetof the analog memories 110 a and 110 b controls an amount of chargesaccumulated in the analog memories 110 a and 110 b to set a state(potential) of the analog memories 110 a and 110 b to a reference state(a reference potential or a reset level). The analog memories 110 a and110 b hold and accumulate analog signals sampled and held by sampletransistors 108 a and 108 b.

Capacitances of the analog memories 110 a and 110 b are set to begreater than the capacitance of the FD 103. It is more desirable to useMOS (Metal Oxide Semiconductor) capacitors or MIM (Metal InsulatorMetal) capacitors that are capacitors having a low leak current (darkcurrent) per unit region, as the analog memories 110 a and 110 b.Accordingly, noise immunity can be improved and a high quality signalcan be obtained.

The second amplification transistors 111 a and 111 b are transistorsthat output, from the sources, the amplified signal obtained byamplifying signals based on the signal charges accumulated in the analogmemories 110 a and 110 b, which are input to the gate terminals. Thesecond amplification transistors 111 a and 111 b and a current source113 connected as a load to the vertical signal line 9 constitute asource follower circuit. The selection transistors 112 a and 112 b aretransistors that select the pixels 1 and transfer outputs of the secondamplification transistors 111 a and 111 b to the vertical signal line 9.On/off of the selection transistor 112 a is controlled by the selectionpulse ΦSEL1 from the vertical scanning circuit 3. On/off of theselection transistor 112 b is controlled by the selection pulse ΦSEL2from the vertical scanning circuit 3.

Among the circuit elements illustrated in FIG. 4, the photoelectricconversion elements 101 a and 101 b are arranged in the first substrate20, the analog memories 110 a and 110 b are arranged in the secondsubstrate 21, and the other circuit elements are arranged in any one ofthe first substrate 20 and the second substrate 21. A dotted line D1 inFIG. 4 indicates a boundary of the first substrate 20 and the secondsubstrate 21. The photoelectric conversion elements 101 a and 101 b, thetransfer transistors 102 a and 102 b, the FD 103, the FD resettransistor 104, and the first amplification transistor 105 are arrangedin the first substrate 20. The current source 106, the clamp capacitor107, the sample transistors 108 a and 108 b, the analog-memory resettransistors 109 a and 109 b, the analog memories 110 a and 110 b, thesecond amplification transistors 111 a and 111 b, and the selectiontransistors 112 a and 112 b are arranged in the second substrate 21.

The amplified signal output from the first amplification transistor 105of the first substrate 20 is output to the second substrate 21 via themicropad 22, the microbump 24 and the micropad 23. Also, the supplyvoltage VDD is transferred between the first substrate 20 and the secondsubstrate 21 via the micropads 25, the microbumps 27 and the micropads26.

While the connector including the micropad 22, the microbump 24, and themicropad 23 is arranged in a path among the source terminal of the firstamplification transistor 105, the one terminal of the current source 106and the one terminal of the clamp capacitor 107 in FIG. 4, the presentinvention is not limited thereto. The connector may be arranged in anyposition on an electrically connected path from the photoelectricconversion elements 101 a and 101 b to the analog memories 110 a and 110b.

FIG. 5 illustrates an example of the boundary of the first substrate 20and the second substrate 21. FIG. 5 illustrates an example in whichdotted lines D1 to D5 can be boundaries between the first substrate 20and the second substrate 21. The boundary of the first substrate 20 andthe second substrate 21 may also be any of the dotted lines D1 to D5 ormay be elsewhere. The dotted line D1 is as described above. In theexample of the dotted line D2, the connector is arranged in a pathbetween the other terminals of the photoelectric conversion elements 101a and 101 b and the drain terminals of the transfer transistors 102 aand 102 b. In the example of the dotted line D3, the connector isarranged in a path among the source terminals of the transfertransistors 102 a and 102 b, the one terminal of the FD 103, the sourceterminal of the FD reset transistor 104, and the gate terminal of thefirst amplification transistor 105.

In the example of the dotted line D4, the connector is arranged in apath between the other terminal of the clamp capacitor 107 and the drainterminals of the sample transistors 108 a and 108 b. In the example ofthe dotted line D5, the connector is arranged in a path among the sourceterminals of the sample transistors 108 a and 108 b, the sourceterminals of the analog-memory reset transistors 109 a and 109 b, theone terminals of the analog memories 110 a and 110 b, and the gateterminals of the second amplification transistors 111 a and 111 b.

All the pixels 1 having the above configuration are classified into aplurality of groups, and each pixel 1 belongs to any one of theplurality of groups. FIG. 6 illustrates a state in which 64 pixels 1 in8 rows×8 columns are classified into a plurality of groups, for example.In FIG. 6, a number Pnm (n: 1 to 8 and m: 1 to 8) is assigned to eachpixel 1 for convenience. In the number Pnm, the digit n indicates a rownumber and the digit m indicate a column number.

According to pixel positions, the pixels 1 are classified into aplurality of groups. FIG. 6A illustrates an example in which two pixelsconstitute one group. The two pixels adjacent in a vertical directionconstitute one group. FIG. 6B illustrates an example in which fourpixels constitute one group. The four pixels continuously arranged inthe vertical direction constitute one group. Because one photoelectricconversion element corresponds to one pixel 1, a group to which thepixel 1 belongs is the same as a group to which the photoelectricconversion element belongs. A plurality of photoelectric conversionelements of the pixels 1 in the same group (two photoelectric conversionelements in the example of FIG. 6A and four photoelectric conversionelements in the example of FIG. 6B) share the FD 103, the FD resettransistor 104, the first amplification transistor 105, the currentsource 106, and the clamp capacitor 107.

Next, an operation of the pixels 1 will be described with reference toFIGS. 7 and 8. Hereinafter, two operation examples will be described.

First Operation Example

FIG. 7 illustrates control signals supplied to the pixel 1 in each rowfrom the vertical scanning circuit 3. Hereinafter, an operation of thepixel 1 in periods T1 to T6 illustrated in FIG. 7 in units of two pixelsillustrated in FIG. 4 will be described. One of the two pixels 1belonging to the same group is referred to as a first pixel, and theother pixel is referred to as a second pixel. A start timing of theoperation (a start timing of the period T1 in FIG. 7) is the same ineach of the plurality of groups.

[Operation of Period T1]

First, the transfer pulses ΦTX1 and ΦTX2 change from being at an “L”(low) level to being at an “H” (high) level to turn the transfertransistors 102 a and 102 b on. At the same time, the FD reset pulseΦRST changes from being at the “L” level to being at the “H” level toturn the FD reset transistor 104 on. Since the period T1 is a periodcommon to all the pixels 1 (hereinafter described as all pixels), thephotoelectric conversion elements 101 a and 101 b of all pixels arereset.

Subsequently, the transfer pulses ΦTX1 and ΦTX2 and the FD reset pulseΦRST change from being at the “H” level to being at the “L” level toturn the transfer transistors 102 a and 102 b and the FD resettransistor 104 off. Accordingly, reset of the photoelectric conversionelements 101 a and 101 b of all the pixels ends, and exposures(accumulations of the signal charges) of all pixels start collectively(simultaneously).

[Operation of Period T2]

A period T2 is a period in an exposure period. First, the clamp andmemory reset pulse ΦCL1 changes from being at an “L” level to being atan “H” level to turn the analog-memory reset transistor 109 a on.Accordingly, the analog memory 110 a is reset. At the same time, thesample pulse ΦSH1 changes from being at an “L” level to being at an “H”level to turn the sample transistor 108 a on. Accordingly, a potentialof the other terminal of the clamp capacitor 107 is reset to the supplyvoltage VDD and the sample transistor 108 a starts the sample and holdof the potential of the other terminal of the clamp capacitor 107.

Subsequently, the FD reset pulse ΦRST changes from being at an “L” levelto being at an “H” level to turn the FD reset transistor 104 on.Accordingly, the FD 103 is reset.

Subsequently, the FD reset pulse ΦRST changes from being at the “H”level to being at the “L” level to turn the FD reset transistor 104 off.Accordingly, the reset of the FD 103 ends. A timing to reset the FD 103may be within the exposure period, but it is possible to further reducenoise due to leak current of the FD 103 by performing the reset of theFD 103 at a timing immediately before the end of the exposure period.

Subsequently, the clamp and memory reset pulse ΦCL1 changes from beingat the “H” level to being at the “L” level to turn the analog-memoryreset transistor 109 a off. Accordingly, the reset of the analog memory110 a ends. At this time point, the clamp capacitor 107 clamps theamplified signal output from the first amplification transistor 105 (theamplified signal after the reset of the FD 103).

[Operation of Period T3]

First, the transfer pulse ΦTX1 changes from being at an “L” level tobeing at an “H” level to turn the transfer transistor 102 a on.Accordingly, the signal charges accumulated in the photoelectricconversion element 101 a are transferred to the FD 103 via the transfertransistor 102 a and accumulated in the FD 103. Accordingly, theexposure (the accumulation of signal charges) of the first pixel ends.Exposure period 1 of FIG. 7 indicates the exposure period (a signalaccumulation period) of the first pixel. Subsequently, the transferpulse ΦTX1 changes from being at the “H” level to being at the “L” levelto turn the transfer transistor 102 a off.

Subsequently, the sample pulse ΦSH1 changes from the “H” level to the“L” level to turn the sample transistor 108 a off. Accordingly, thesample transistor 108 a ends the sample and hold of the potential of theother terminal of the clamp capacitor 107.

[Operation of Periods T4 and T5]

An operation of the periods T2 and T3 described above is the operationof the first pixel. An operation of the periods T4 and T5 corresponds tothe operation of the periods T2 and T3 and is an operation of the secondpixel. An operation of the period T4 is the same as the operation of theperiod T2. Since the operation of the period T5 is the same as theoperation of the period T3, a description of the operation of theperiods T4 and T5 will be omitted. Exposure period 2 of FIG. 7 indicatesan exposure period (a signal accumulation period) of the second pixel.

Hereinafter, a change in a potential of the one terminal of the analogmemory 110 a of the first pixel will be described. The same applies to achange in a potential of the one terminal of the analog memory 110 b ofthe second pixel.

When a change in the potential of the one terminal of the FD 103 as thesignal charges are transferred from the photoelectric conversion element101 a to the FD 103 after the reset of the FD 103 has ended is ΔVfd anda gain of the first amplification transistor 105 is α1, a change ΔVamp1in the potential of the source terminal of the first amplificationtransistor 105 as the signal charges are transferred from thephotoelectric conversion element 101 a to the FD 103 is α1×ΔVfd.

When a total gain of the sample transistor 108 a and the analog memory110 a is α2, a change ΔVmem in the potential of the one terminal of theanalog memory 110 a due to the sample and hold of the sample transistor108 a after the signal charges are transferred from the photoelectricconversion element 101 a to the FD 103 is α2×ΔVamp1, i.e., α1×α2×ΔVfd.Since the potential of the one terminal of the analog memory 110 a at atime point at which the reset of the analog memory 110 a has ended isthe supply voltage VDD, the potential Vmem of the one terminal of theanalog memory 110 a sampled and held by the sample transistor 108 aafter the signal charges are transferred from the photoelectricconversion element 101 a to the FD 103 is represented by the followingEquation (1). In Equation (1), ΔVmem<0 and ΔVfd<0.

$\begin{matrix}\begin{matrix}{{Vmem} = {{VDD} + {\Delta \; {Vmem}}}} \\{= {{VDD} + {\alpha \; 1 \times \alpha \; 2 \times \Delta \; {Vfd}}}}\end{matrix} & (1)\end{matrix}$

Further, α2 is represented by the following Equation (2). In Equation(2), CL is a capacitance value of the clamp capacitor 107, and CSH is acapacitance value of the analog memory 110 a. In order to reduce adecrease in the gain, it is more desirable for the capacitance value CLof the clamp capacitor 107 to be greater than the capacitance value CSHof the analog memory 110 a.

$\begin{matrix}{{\alpha \; 2} = \frac{CL}{{CL} + {CSH}}} & (2)\end{matrix}$

[Operation of Period T6]

In the period T6, the signals based on the signal charges accumulated inthe analog memories 110 a and 110 b are sequentially read for each row.First, readout of a signal from the first pixel is performed. Theselection pulse ΦSEL1 changes from being at an “L” level to being at an“H” level to turn the selection transistor 112 a on. Accordingly, asignal based on the potential Vmem shown in Equation (1) is output tothe vertical signal line 9 via the selection transistor 112 a.Subsequently, the selection pulse ΦSEL1 changes from being at the “H”level to being at the “L” level to turn the selection transistor 112 aoff.

Subsequently, the clamp and memory reset pulse ΦCL1 changes from beingat an “L” level to being at an “H” level to turn the analog-memory resettransistor 109 a on. Accordingly, the analog memory 110 a is reset.Subsequently, the clamp and memory reset pulse ΦCL1 changes from beingat the “H” level to being at the “L” level to turn the analog-memoryreset transistor 109 a off.

Subsequently, the selection pulse ΦSEL1 changes from being at an “L”level to being at an “H” level to turn the selection transistor 112 aon. Accordingly, a signal based on the potential of the one terminal ofthe analog memory 110 a when the analog memory 110 a is reset is outputto the vertical signal line 9 via the selection transistor 112 a.Subsequently, the selection pulse ΦSEL1 changes from being at the “H”level to being at the “L” level to turn the selection transistor 112 aoff.

The column processing circuit 4 generates a difference signal that takesa difference between the signal based on the potential Vmem shown inEquation (1) and the signal based on the potential of the one terminalof the analog memory 110 a when the analog memory 110 a has been reset.This difference signal is a signal based on a difference between thevoltage Vmem shown in Equation (1) and the supply voltage VDD. Further,the difference signal is a signal based on the difference ΔVfd betweenthe potential of the one terminal of the FD 103 immediately after thesignal charges accumulated in the photoelectric conversion element 101 ais transferred to the FD 103 and the potential of the FD 103 immediatelyafter the one terminal of the FD 103 is reset. Thus, it is possible toobtain a signal component based on the signal charges accumulated in thephotoelectric conversion element 101 a, from which a noise component dueto the reset of the analog memory 110 a and a noise component due to thereset of the FD 103 have been suppressed.

The signal output from the column processing circuit 4 is output to thehorizontal signal line 10 by the horizontal readout circuit 5. Theoutput amplifier 6 processes the signal output to the horizontal signalline 10 and outputs a resultant signal from the output terminal 11 as apixel signal. Then, the readout of the signal from the first pixel ends.

Subsequently, the readout of the signal from the second pixel isperformed. Since the readout of the signal from the second pixel is thesame as the readout of the signal from the first pixel, a description ofthe readout of the signal from the second pixel will be omitted.

A period to read the signal from the pixel 1 in the period T6 differs ineach row. FIG. 8 illustrates an operation of each pixel 1 in the periodT6. In FIG. 8, the clamp and memory reset pulse ΦCL1 of the pixel 1 ofan odd row (row i), which is the first pixel, is ΦCL1-i, and theselection pulse ΦSEL1 is ΦSEL1-i. Further, in FIG. 8, the clamp andmemory reset pulse ΦCL2 of the pixel 1 of an even row (row j), which isthe second pixel, is ΦCL2-j, and the selection pulse ΦSEL2 is ΦSEL2-j.Further, in FIG. 8, a case in which the number n of rows is an evennumber is illustrated.

The period T6 includes periods T6-1, T6-2, . . . , T6-N. In the periodT6-1, signals are read from pixels 1 in a first row and a second row. Anoperation of the pixel 1 in the period T6-1 is the same as the operationof the pixel 1 in the period T6 in FIG. 7. In the period T6-2, signalsare read from pixels of a third row and a fourth row. An operation ofthe pixel 1 in the period T6-2 is also the same as the operation of thepixel 1 in the period T6 in FIG. 7. Even for the pixels 1 of a fourthrow and subsequent rows, the same operation is performed for each row.In the period T6-N, signals are read from pixels 1 of the last row (annth row). The operation of the pixel 1 in the period T6-N is also thesame as the operation of the pixel 1 in the period T6 in FIG. 7. Throughthe above operation, signals are read from all the pixels.

In the above operation, the FD 103 must hold the signal chargestransferred from photoelectric conversion elements 101 a and 101 b tothe FD 103 until to a readout timing of each pixel 1. If a noise isgenerated during a period in which the FD 103 holds the signal charges,the noise is superimposed on the signal charges held by the FD 103, thusdegrading signal quality (S/N).

Primary causes of the noise generated during the period in which the FD103 holds the signal charges (hereinafter referred to as a holdingperiod) are charges due to leak current of the FD 103 (hereinafterdescribed as leak charges) and charges due to light incident on portionsother than the photoelectric conversion elements 101 a and 101 b(hereinafter referred to as light charges). When the leak charges andthe light charges generated in a unit time are qid and qpn,respectively, and a length of the holding period is tc, noise charges Qngenerated during the holding period become (qid+qpn) tc.

It is assumed that the capacitance of the FD 103 is Cfd, the capacitanceof the analog memories 110 a and 110 b is Cmem, and a ratio of Cfd andCmem (Cmem/Cfd) is A. It is also assumed that a gain of the firstamplification transistor 105 is α1, and a total gain of the analogmemories 110 a and 110 b and the sample transistors 108 a and 108 b isα2, as described above. When the signal charges generated in thephotoelectric conversion elements 101 a and 101 b during the exposureperiod are Qph, the signal charges held in the analog memories 110 a and110 b after the end of the exposure period become A×α1×α2×Qph.

The signal based on the signal charges transferred from thephotoelectric conversion element 101 to the FD 103 is sampled and heldby the sample transistor 108 and stored in the analog memory 110 in theperiod T3 or T5. Accordingly, a time from the signal charges beingtransferred to the FD 103 to the signal charges being stored in theanalog memory 110 is short and the noise generated in the FD 103 isnegligible. Assuming that the noise generated in the period in which theanalog memory 110 holds the signal charges is Qn as described above, S/Nbecomes A×α1×α2×Qph/Qn.

Meanwhile, as in the prior art described in Patent Document 2, S/N whenthe signal charges held in the capacitor accumulation units are readfrom the pixel via the amplification transistor becomes Qph/Qn.Therefore, S/N of the present embodiment is A×α1×α2 times the S/N of theprior art. It is possible to reduce degradation of signal quality bysetting the capacitance value of the analog memories 110 a and 110 b sothat A×α1×α2 is greater than 1 (e.g., by setting the capacitance valueof the analog memory 110 to be sufficiently greater than the capacitancevalue of the FD 103).

In the first operation example, the start timing of the exposure is thesame in all the pixels, but an end timing of the exposure of therespective pixels 1 in the same group differs, as shown in exposureperiods 1 and 2 of FIG. 7. However, a difference in the exposure periodis small.

Second Operation Example

FIG. 9 illustrates control signals supplied to the pixel 1 in each rowfrom the vertical scanning circuit 3. Hereinafter, an operation of thepixel 1 in periods T1 to T6 illustrated in FIG. 9 in units of two pixelsillustrated in FIG. 4 will be described. One pixel 1 of the two pixels 1belonging to the same group is referred to as a first pixel, and theother pixel is referred to as a second pixel. A start timing of theoperation (a start timing of the period T1 in FIG. 9) is the same ineach of the plurality of groups described above. Hereinafter, onlyportions different from those in the first operation example will bedescribed.

Operations in the periods T1 and T1′ differ from those in the operationillustrated in FIG. 7. In the period T1, reset of the photoelectricconversion element 101 a is performed only for the first pixel. Further,in the period T1′, reset of the photoelectric conversion element 101 bis performed only for the second pixel. Exposure period 1 of FIG. 9indicates an exposure period (a signal accumulation period) of the firstpixel, and exposure period 2 indicates an exposure period (a signalaccumulation period) of the second pixel.

A start timing of the period T1′ is set so that lengths of exposureperiod 1 and exposure period 2 are the same. Accordingly, in the secondoperation example, since lengths of the exposure periods of all pixelsare the same, it is possible to obtain a higher quality signal. Further,in the second operation example, it is possible to reduce deteriorationof signal quality, as in the first operation example.

Next, arrangement positions of the connector including the micropads 22,the micro bumps 24, the micropads 23, and the pixels 1 will bedescribed, FIG. 10 illustrates an example of 64 pixels 1 in 8 rows×8columns in which 16 pixels in 4 rows×4 columns constitute one group asan example. In FIG. 10, a number Pnm (n: 1 to 8 and m: 1 to 8) forconvenience is assigned to each pixel 1. The digit n of the number Pnmindicates a row number, and the digit m indicates a column number.

In the shown example, 16 pixels 1 having pixel numbers P 11 to P14, P21to P24, P31 to P34, and P41 to P44 constitute a group 301. Further, 16pixels 1 having pixel numbers P15 to P18, P25 to P28, P35 to P38, andP45 to P48 constitute a group 302. Further, 16 pixels 1 having pixelnumbers P51 to P54, P61 to P64, P71 to P74, and P81 to P84 constitute agroup 303. Further, 16 pixels 1 having pixel numbers P55 to P58, P65 toP68, P75 to P78, and P85 to P88 constitute a group 304.

Since one photoelectric conversion element corresponds to one pixel 1, agroup to which the pixel 1 belongs is the same as a group to which thephotoelectric conversion element belongs. A plurality of photoelectricconversion elements of the 16 pixels 1 in the same group share the FD103, the FD reset transistor 104, the first amplification transistor105, the current source 106, and the clamp capacitor 107.

Further, since the plurality of photoelectric conversion elements of thepixels 1 included in the respective groups 301 to 304 share the FD 103,the FD reset transistor 104, the first amplification transistor 105, thecurrent source 106, and the clamp capacitor 107, one connector 300 isarranged for each of the groups 301 to 304. In the group 301, theconnector 300 is arranged in positions of pixel numbers P22, P23, P32and P33. Further, in the group 302, the connector 300 is arranged inpositions of pixel numbers P26, P27, P36 and P37. Further, in the group303, the connector 300 is arranged in positions of pixel numbers P62,P63, P72, and P73. Further, in the group 304, the connector 300 isarranged in the positions of pixel numbers P66, P67, P76, and P77.

Further, an arrangement pattern of the connector 300 is not limited to apattern illustrated in FIG. 10, and the number of pixels 1 constitutinga group may be any number. For example, only one pixel 1 may constitutea group and the one pixel may be connected to the second substrate 21using one connector 300.

Next, an arrangement position of the dummy connector will be described.As described above, the connector 300 (a real connector) is arranged ina region in which the pixel 1 is arranged. Further, a chip of amultilayer substrate (e.g., a solid-state imaging device or an imagingapparatus) in which the first substrate 20 in which the photoelectricconversion elements 101 are arranged and the second substrate 21 inwhich some or all of circuits performing processing of signals output bythe photoelectric conversion elements 101 are arranged are connectedusing the connection units 300 is manufactured. As a process order ofmanufacturing this chip of a multilayer substrate, an order ofconnecting a semiconductor wafer (a first semiconductor wafer) havingthe first substrate 20 formed therein and a semiconductor wafer (asecond semiconductor wafer) having the second substrate 21 formedtherein using the connection units 300 and then cutting a resultantwafer into a chip through dicing (singulation) is considered. Some orall of the circuits performing processing of signals output by thephotoelectric conversion elements 101 are referred to as peripheralcircuits. Further, the peripheral circuit may include a wiring circuit.

In this case, since the connectors 300 are arranged in the region inwhich the pixels 1 are arranged, a mechanical strength to connect thefirst substrate 20 and the second substrate 21 is high. On the otherhand, the peripheral connectors including the micropads 25, themicrobumps 27, and the micropads 26 are arranged in the regions (e.g.,the peripheral circuit region in which the peripheral circuits arearranged or the empty region in which nothing is arranged) other thanthe region in which the pixels 1 are arranged, as illustrated in FIGS.3A and 3B, but the number of peripheral connectors is smaller than thenumber of connectors 300. Accordingly, a mechanical strength to connectthe first substrate 20 with the second substrate 21 is low in theregions other than the region in which the pixels 1 are arranged.

Accordingly, when dicing is performed to cut out chips from thesemiconductor wafer, the chip is likely to be cracked and chipped,failing to withstand intensity of the dicing. Further, the semiconductorwafer is not completely flat, but slightly distorted. When semiconductorwafers are connected, the semiconductor wafers are connected whilesuppressing distortion through weighting on a flat stage. For thisreason, the distortion is recovered after the wafer is cut into chips,and the bumps are likely to be disconnected.

Thus, in the present embodiment, the dummy connectors are arranged inthe regions (e.g., the peripheral circuit region and the empty region)other than the region in which the pixels 1 are arranged. Even in theregions other than the region in which the pixels 1 are arranged, themechanical strength to connect the first substrate 20 and the secondsubstrate 21 increases. A configuration of the dummy connector is thesame as the configuration of the connector 300. That is, the micropadsarranged in the first substrate 20, the microbumps, and the micropadsarranged in the second substrate 21 constitute the dummy connectorsconnecting the first substrate 20 with the second substrate 21.

The dummy connectors are formed in a substantially columnar shapebetween the first substrate 20 and the second substrate 21.

FIGS. 11A and 11B illustrate a planar structure (FIG. 11A) and across-sectional structure (FIG. 11B) of a substrate in which the firstsubstrate 20 and the second substrate 21 are bonded. A cross-sectionalview illustrated in FIG. 11B is a cross-sectional view taken along lineB-B′ illustrated in FIG. 11A. In an example illustrated in FIG. 11A, apixel region 401 in which the pixels 1 are arranged, a peripheralcircuit region 402 in which peripheral circuits are arranged, and anempty region 403 in which nothing is arranged are included in a regionof the first substrate 20.

Further, connectors 300 (real connectors) for transferring signalsbetween the first substrate 20 and the second substrate 21 are arrangedin the pixel region 401. However, the connectors 300 are not arranged inthe peripheral circuit region 402 and the empty region 403, which areregions other than the pixel region 401. As illustrated in FIG. 11A,dummy connectors 500 that do not perform transfer of signals arearranged in the peripheral circuit region 402 and the empty region 403,which are regions other than the pixel region 401.

Further, in the illustrated example, an arrangement interval of thedummy connectors 500 is the same as an arrangement interval of theconnectors 300 arranged in the pixel region 401. For example, when apixel pitch of the pixels 1 is 5 μm and 16 pixels 1 in 4 rows and 4columns use the same connector 300, the connectors 300 and the dummyconnectors 500 are arranged at intervals of 20 μm.

A method of manufacturing the chip formed as described above isperformed through the following process.

The first substrate 20 including circuit elements and the secondsubstrate 21 including the output amplifier 6 are bonded via theconnectors 300.

Also, a connector arranging process is performed to arrange the dummyconnectors 500 supporting the first and second bonded substrates 20 and21 in the regions other than the region in which the pixels 1 arearranged, i.e., in the regions in which the connectors 300 are notarranged.

Through this process, a chip is manufactured.

Thus, as the dummy connectors 500 that do not transfer signals arearranged in the regions (e.g., the peripheral circuit region 402 and theempty region 403) other than the pixel region 401, mechanical connectionstrength of the first substrate 20 and the second substrate 21increases. Accordingly, cracks and chipping when the chip is cut outthrough dicing can be reduced or prevention of the disconnection due todistortion of the substrate can be reduced. Thus, it is possible tomanufacture a high-yield chip of a multilayer substrate (e.g., asolid-state imaging device or an imaging apparatus).

Further, it is possible to reduce influence of peripheral circuits evenwhen chipping occurs.

In the example described above, the dummy connectors 500 do not performtransfer of signals between the first substrate 20 and the secondsubstrate 21. However, for example, the dummy connectors 500 may be usedas a power line or a ground line of the first substrate 20 and thesecond substrate 21 to enhance the power and the ground of the firstsubstrate 20 and the second substrate 21.

Further, the arrangement of the dummy connectors 500 is not limited tothe example shown in FIGS. 11A and 11B and may be any arrangementcapable of increasing the mechanical connection strength of the firstsubstrate 20 and the second substrate 21.

FIG. 12 is a plan view illustrating a planar structure of a substrate inwhich the first substrate 20 and the second substrate 21 are bonded. Inan example illustrated in FIG. 12, an arrangement interval of the dummyconnectors 500 is greater than that in the example illustrated in FIGS.11A and 11B. A pixel region 401, a peripheral circuit region 402, and anempty region 403 included in a region of the first substrate 20 are thesame as those in the example illustrated in FIGS. 11A and 11B. Further,an arrangement of the connectors 300 is the same as that in the exampleillustrated in FIGS. 11A and 11B. In the shown example, an arrangementinterval of the dummy connectors 500 is twice the arrangement intervalof the connectors 300. Even in this case, since mechanical connectionstrength of the first substrate 20 and the second substrate 21increases, cracks and chipping when the chip is cut out through dicingcan be reduced or prevention of the disconnection due to distortion ofthe substrate can be reduced. Accordingly, it is possible to manufacturea high-yield chip of a multilayer substrate (e.g., a solid-state imagingdevice or an imaging apparatus).

Second Embodiment

Next, a second embodiment of the present invention will be described.There is a method of bonding a semiconductor wafer having a firstsubstrate 20 formed therein and a semiconductor wafer having a secondsubstrate 21 formed therein through weighting of the semiconductorwafers when the semiconductor wafers are bonded. When the semiconductorwafers are bonded in this way, if there are elements constitutingcircuits, such as transistors and wirings, under the dummy connectors500 arranged in the peripheral circuit region 402, there is apossibility of the circuit components being altered due to the weightingand circuit characteristics being changed.

In peripheral circuits included in a solid-state imaging device(peripheral circuits that are some or all of circuits that performprocessing of a signal output by the photoelectric conversion element101), the same circuits are arranged regularly at a pixel pitch or at apitch that is an integer multiple of the pixel pitch in each column. Inan example illustrated in FIG. 13, column ADC circuits (analog-digitalconversion circuits) 601A and 601B are arranged regularly at a pixelpitch or at a pitch being an integer multiple of the pixel pitch in eachcolumn. Accordingly, a circuit in which the dummy connector 500 ispresent and a circuit in which the dummy connector 500 is not presenthave different circuit characteristics due to an interval between thedummy bumps arranged in the peripheral circuit region 402, which maycause a fixed pattern noise. For example, in the example illustrated inFIG. 13, the dummy connector 500 is present in the column ADC circuit601A included in the peripheral circuit. Since the dummy connector 500is not present in the column ADC circuit 601B, the column ADC circuit601A and the column ADC circuit 601B have different circuitcharacteristics, which may cause the fixed pattern noise.

Therefore, in the present embodiment, in order for the circuits includedin the peripheral circuit to have the same circuit characteristics, anarrangement of the dummy connectors 500, which are arranged in theperipheral circuit region 402, is considered. An arrangement of thedummy connectors 500 to be arranged in a region other than theperipheral circuit region 402 is the same as the arrangement of thedummy connectors 500 in the first embodiment.

FIG. 14 is a schematic diagram illustrating an arrangement pattern ofthe dummy connectors 500 arranged in the peripheral circuit region 402in the present embodiment. In the illustrated example, column ADCcircuits 601 are arranged in the peripheral circuit region 402. Further,the dummy connector 500 is arranged on each column ADC circuit 601.Since the respective column ADC circuits 601 have the same circuitcharacteristics by arranging the dummy connectors 500 on all the columnADC circuits 601, it is possible to suppress generation of the fixedpattern noise.

The arrangement pattern of the dummy connectors 500 is not limited tothe arrangement pattern illustrated in FIG. 14, and may be any patterncapable of suppressing the generation of the fixed pattern noise. FIG.15 is a schematic diagram illustrating an arrangement pattern of thedummy connectors 500 arranged in the peripheral circuit region 402 inthe present embodiment. In the illustrated example, the dummy connector500 is arranged in the middle of two column ADC circuits 601. In thiscase, the two column ADC circuits 601 are configured so that a circuitpattern of the two column ADC circuits 601 is symmetric to the dummyconnector 500. With this configuration, an arrangement position of thedummy connector 500 is on the same element or wiring in the left columnADC circuit 601 and the right column ADC circuit 601. Accordingly, sincethe dummy connector 500 is on the same element or wiring in each columnADC circuit 601, the difference between the characteristics of therespective column ADC circuits 601 becomes substantially the same andthe generation of the fixed pattern noise can be suppressed.

If the dummy connector 500 is arranged in each circuit arranged in theperipheral circuit region 402, i.e., at a pixel pitch or at a pitch thatis an integer multiple of the pixel pitch as described above, a circuitcharacteristic difference due to the arrangement positions of the dummyconnectors 500 is not generated. For example, when the circuit arrangedin the peripheral circuit region 402 is the column ADC circuit 601, aresistance value, a capacitance value or a characteristic of thetransistors in the column ADC circuit 601 is uniform in each column.Accordingly, it is possible to reduce the characteristic difference ofthe peripheral circuit due to the arrangement positions of the dummyconnectors 500. It is also possible to suppress degradation of thesignal output from the photoelectric conversion element 101, i.e.,deterioration of image quality of an image captured by the solid-stateimaging device.

In the example described above, the case in which the elements or thewirings constituting the circuits are present in the arrangementpositions of the dummy connectors 500 has been described. However, it isalso possible to reduce a change in the circuit characteristics byarranging the dummy connectors 500 in positions that do not affect theelements or wirings in the circuits. Further, while the description hasbeen given using the column ADC circuit 601 as an example of the circuitincluded in the peripheral circuit region 402 in the example describedabove, the present invention is not limited thereto. For example, thecircuit is not limited to the horizontal scanning circuit such as thecolumn ADC circuit 601, and even when the dummy connectors 500 arearranged in the peripheral circuit region 402 including a plurality ofunit circuits, variations in characteristics of the unit circuits can bereduced and the generation of the fixed pattern noise can be suppressed.

Third Embodiment

Hereinafter, a third embodiment of the present invention will bedescribed. A difference between the first embodiment and the presentembodiment is that, in the present embodiment, the dummy connectors 500are not arranged in the peripheral circuit region 402. Otherconfigurations are the same as those of the first embodiment.

FIG. 16 is a plan view illustrating a planar structure of a substrate inwhich the first substrate 20 and the second substrate 21 are bonded. Adifference between an example illustrated in FIG. 16 and the exampleillustrated in FIGS. 11A and 11B is that, in the example illustrated inFIG. 16, the dummy connectors 500 are not arranged in the peripheralcircuit region 402. The dummy connectors 500 are arranged in an emptyregion 403. By not arranging the dummy connectors 500 in the peripheralcircuit region 402 but arranging the dummy connectors 500 only in theempty region 403 in this way, it is possible to prevent a change incharacteristics of circuits arranged in the peripheral circuit region402 while increasing mechanical connection strength between the firstsubstrate 20 and the second substrate 21. Further, it is unnecessary todetermine the arrangement of the dummy connectors 500 in considerationof the arrangement of the circuits arranged in the peripheral circuitregion 402, thus improving the degree of freedom of a circuit layout.

A method of arranging the dummy connectors 500 is not limited to theexample illustrated in FIG. 16. FIG. 17 is a plan view illustrating aplanar structure of a substrate in which the first substrate 20 and thesecond substrate 21 are bonded. In an example illustrated in FIG. 17, anarrangement of some dummy connectors 500 is omitted, unlike the exampleillustrated in FIGS. 11A and 11B. In the illustrated example, anarrangement of the dummy connector 500 to be arranged in a region 700included in the empty region 403 is omitted.

In other words, in this example, a distance between adjacent dummyconnectors 500 is changed. For concrete description, one of a pluralityof dummy connectors 500 is defined as a dummy connector 500 a, anddifferent directions D1 and D2 from the dummy connector 500 a, which isa start point, are defined. The dummy connector 500 adjacent in thedirection D1 with respect to the dummy connector 500 a is defined as aconnector 500 b, and the dummy connector 500 adjacent in the directionD2 with respect to the dummy connector 500 a is defined as a connector500 c. In this case, the distance between the dummy connector 500 a andthe dummy connector 500 b is set to be greater than a distance betweenthe dummy connector 500 a and the dummy connector 500 c.

Accordingly, it is possible to reduce mechanical connection strengthbetween a semiconductor wafer having the first substrate 20 formedtherein and a semiconductor wafer having the second substrate 21 formedtherein. Specifically, it is possible to reduce the mechanicalconnection strength of the two semiconductor wafers between the dummyconnectors 500 a and 500 b. It is also possible to reduce the pressureto be applied to the semiconductor wafer having the first substrate 20formed therein and the semiconductor wafer having the second substrate21 formed therein.

FIG. 18 is a plan view illustrating a planar structure of the substratein which the first substrate 20 and the second substrate 21 are bonded.In an example illustrated in FIG. 18, arrangement positions of somedummy connectors 500 are shifted from arrangement positions at equalintervals, unlike the example illustrated in FIGS. 11A and 11B. In theillustrated example, arrangement positions of dummy connectors 500arranged in a region 701 included in the empty region 403 are shiftedfrom arrangement positions at equal intervals. Accordingly, it ispossible to efficiently enhance connection strength of a region in whichmechanical strength of the connection between the semiconductor waferhaving the first substrate 20 formed therein and the semiconductor waferhaving the second substrate 21 formed therein is low. Further,accordingly, when the semiconductor wafer having the first substrate 20formed therein and the semiconductor wafer having the second substrate21 formed therein are bonded and then diced, it is possible to preventthe semiconductor wafer having the first substrate 20 formed therein andthe semiconductor wafer having the second substrate 21 formed thereinfrom being disconnected from each other.

Fourth Embodiment

Hereinafter, a fourth embodiment of the present invention will bedescribed.

A difference between the first embodiment and the present embodiment isthat, in the present embodiment, the dummy connector 500 is connected toa ground wiring provided in the first substrate 20 or the secondsubstrate 21.

As illustrated in FIG. 19, in this example, the first substrate 20 isformed by stacking a semiconductor substrate (not shown) and interlayerinsulating films 20 a, 20 b, and 20 c. Connection wirings 801 and 802are formed between the interlayer insulating films 20 a and 20 b andbetween the interlayer insulating films 20 b and 20 c, respectively.Vias 804 and 805 are formed in the interlayer insulating films 20 a and20 b. Connectors 300 are connected to a photoelectric conversion unit(not shown) via the vias 804 and 805, the connection wirings 801 and 802and vias (not shown).

A ground wiring 807 (a first ground wiring) is provided between theinterlayer insulating films 20 a and 20 b. A dummy connector 500 isconnected to the ground wiring 807 via the via 804.

Similarly, the second substrate 21 is formed by stacking a semiconductorsubstrate (not shown) and interlayer insulating films 21 a, 21 b and 21c. Connection wirings 811 and 812 are formed between the interlayerinsulating films 21 a and 21 b and between the interlayer insulatingfilms 21 b and 21, respectively. The vias 814 and 815 are formed in theinterlayer insulating films 21 a and 21 b. The connector 300 isconnected to the above-described output amplifier 6 via the vias 814 and815 and the connection wirings 811 and 812.

A ground line 817 (a second ground wiring) is provided between theinterlayer insulating films 21 a and 21 b. The dummy connector 500 isconnected to the ground wiring 817 via the via 814.

The ground wirings 807 and 817 may be formed of a metal such as Al or Cuthrough the same semiconductor process as the connection wirings 801 and811.

A resin layer 821 is provided between the interlayer insulating film 20a and the interlayer insulating film 21 a to cover outer peripheralsurfaces of the connector 300 and the dummy connector 500.

In the manufacturing method of the present embodiment of manufacturing achip formed in this manner, the ground wiring 807 is formed in the firstsubstrate 20 and the ground wire 817 is formed in the second substrate21 using a known photolithography technology prior to performing theconnector arranging process in the first embodiment. The vias 804, 805,814 and 815 and the like are formed in the substrates 20 and 21.

Next, in the connector arranging process, when the dummy connector 500is arranged, the dummy connector 500 is connected to the ground wirings807 and 817 via the vias 804 and 814.

The substrates 20 and 21 connected to each other by the connectors 300and the dummy connectors 500 may be subjected to a process such as dryetching in a state in which one (e.g., the second substrate 21) of thesubstrates 20 and 21 is attached to a stage of a manufacturingapparatus. In dry etching, since the substrates are processed by anactive gas, a temperature of the first substrate 20 becomes high. Heatof the second substrate 21 attached to the stage can be dissipateddirectly toward the manufacturing apparatus even when its temperaturerises. However, heat of the first substrate 20 cannot be dissipatedtoward the manufacturing apparatus other than via the second substrate21 when its temperature rises. Further, since the vicinity of thesubstrates 20 and 21 is normally in a vacuum state, the temperature ofthe first substrate 20 easily rises at the time of dry etching.

In the chip and the chip manufacturing method of the present embodiment,both ends of the dummy connector 500 are connected to the ground wirings807 and 817. Accordingly, it is possible to effectively transfer heat ofthe first heated substrate 20 to the second substrate 21 via the groundwiring 807, the dummy connector 500 and the ground wiring 817, whichhave high thermal conductivity. That is, it is possible to increase theefficiency of heat transfer between the first substrate 20 and thesecond substrate 21. Thus, it is possible to dissipate the heatgenerated in the first substrate 20 toward the manufacturing apparatusvia the second substrate 21.

When linear expansion coefficients of respective members constitutingthe first substrate 20 differ from each other, cracking or peeling mayoccur at an interface between the members when the first substrate 20 isheated. Further, the first substrate 20 expands due to temperature rise,but the second substrate 21 expands little because its heat isdissipated. Accordingly, cracks and peeling at the interface between themembers or cracks in the member may occur. It is possible to decreasethe temperature of the first substrate 20 by increasing the efficiencyof heat transfer between the first substrate 20 and the second substrate21 in the chip of the present embodiment, thereby suppressing occurrenceof peeling or cracks described above.

Since the ground wiring is generally formed to be greater than otherconnection wirings, heat can be effectively delivered between the firstsubstrate 20 and the ground wiring 807 and between the second substrate21 and the ground wiring 817.

These effects can be similarly obtained even when the first substrate 20is mounted on the stage of the manufacturing apparatus.

In the present embodiment, the dummy connector 500 is connected to theground wiring 807 provided in the first substrate 20 and the groundwiring 817 provided in the second substrate 21. However, the dummyconnector 500 may be connected to only one of the ground wirings 807 and817.

Even with this configuration, heat transfer efficiency between one ofthe substrates 20 and 21 and the dummy connector 500 increases. As aresult, heat transfer efficiency between the first substrate 20 and thesecond substrate 21 is possible to be increased.

Fifth Embodiment

Next, a fifth embodiment of the present invention will be described.

A difference between the fourth embodiment and the present embodiment isthat, in the present embodiment, the dummy connectors 500 are connectedto a heat conduction pattern provided in the first substrate 20 or thesecond substrate 21. Another difference is that at least some of thedummy connectors 500 connected to the heat conduction patterns and theheat conduction patterns are diced and removed.

As illustrated in FIG. 20, a heat conduction pattern (a first heatconduction pattern) 808 is provided between the interlayer insulatingfilms 20 a and 20 b of the first substrate 20. The heat conductionpattern 808 is insulated from circuit elements including a photoelectricconversion unit, which are not shown, by the interlayer insulating films20 a and 20 b. A heat conduction pattern 818 (a second heat conductionpattern) is provided between the interlayer insulating films 21 a and 21b of the second substrate 21. The heat conduction pattern 818 isinsulated from the output amplifier 6 by the interlayer insulating films21 a and 21 b. The heat conduction patterns 808 and 818 may be formed ofa metal such as Al or Cu through the same semiconductor process as theconnection wirings 801 and 811.

Each of the dummy connectors 500 d that are some of a plurality of dummyconnectors 500 provided in the chip is connected to the ground wirings807 and 817 via the vias 804 and 814, as in the above embodiment. Eachof the dummy connectors 500 e that are others of the plurality of dummyconnectors 500 is connected to the heat conduction patterns 808 and 818.When dicing is performed, the dummy connectors 500 e are removedtogether with the heat conduction patterns 808 and 818.

Specifically, as illustrated in FIG. 21, a region R1 is a region inwhich the above-described pixels 1 are arranged, and a plurality ofconnectors 300 are arranged in the region R1. A region R2 is a regionthat becomes a diced and singulated chip, and is a unit region in whicheach chip is cut from the substrates 20 and 21. A plurality ofconnectors 300 and dummy connectors 500 d are arranged in the region R2.

Dummy connectors 500 e are arranged between the adjacent regions R2. Aregion R4 in which the dummy connectors 500 e are arranged becomes ascribe line to be used when the dicing is performed. That is, when thechip is singulated by dicing, the dummy connectors 500 e are removedtogether with the heat conduction patterns 808 and 818. In this example,the dummy connectors 500 e are arranged in one column between theadjacent regions R2.

In the manufacturing method of the present embodiment of manufacturingthe chip formed in this manner, the heat conduction pattern 808 isformed in the first substrate 20 and the heat conduction pattern 818 isformed in the second substrate 21 prior to performing the connectorarranging process in the fourth embodiment.

Next, in the connector arranging process, the dummy connector 500 d isconnected to the ground wiring 807 and 817 via the vias 804 and 814, andthe dummy connector 500 e is connected to the heat conduction patterns808 and 818 via the vias 804 and 814.

Also, in the removal process, all of the heat conduction patterns 808and 818 and the dummy connectors 500 e included in the region R4 areremoved by dicing.

Through this process, the singulated chip is manufactured.

In the chip and the chip manufacturing method of the present embodiment,for example, when the second substrate 21 is mounted on the stage of themanufacturing apparatus and subjected to a process such as dry etching,heat generated in the first substrate 20 can be more effectivelydissipated toward the manufacturing apparatus 21 via the secondsubstrate 21 by the dummy connectors 500 d and 500 e.

Further, since the dummy connectors 500 e are removed when the substrateis singulated and used as a chip, it is possible to suppress transfer ofthe heat between the substrates 20 and 21.

Further, in the present embodiment, while all of the heat conductionpatterns 808 and 818 and the dummy connectors 500 e have been removed inthe removing process, only some of the heat conduction patterns 808 and818 and the dummy connectors 500 e may be removed. This is because it ispossible to suppress transfer of the heat between the substrates 20 and21 even with such a configuration.

Further, in the chip of the present embodiment, the heat conductionpatterns 808 and 818 are connected to the dummy connector 500 e.However, one of the heat conduction patterns 808 and 818 may not beprovided in the substrates 20 and 21 or neither of the heat conductionpatterns 808 and 818 may be provided. Even with this configuration, whenthe process such as dry etching is performed, it is possible toeffectively dissipate heat generated in the first substrate 20 towardthe manufacturing apparatus via the second substrate 21 by the dummyconnectors 500 d and 500 e.

In the present embodiment, while the dummy connectors 500 e have beenarranged in one column between the adjacent regions R2, the dummyconnectors 500 e may be arranged in a plurality of columns between theadjacent regions R2.

Further, in the present embodiment, the dummy connectors 500 d may notbe included in the chip and all the dummy connectors 500 may be removedby dicing.

While the embodiments of the present invention have been described indetail with reference to the drawings, a specific configuration is notlimited to the embodiments described above and includes designmodifications without departing from the scope and spirit of the presentinvention.

For example, in the solid-state imaging device according to the presentembodiment, the two substrates may be connected by the connectors 300and the dummy connectors 500, or three or more substrates may beconnected by the connectors 300 and the dummy connectors 500.

Sixth Embodiment

Next, a sixth embodiment of the present invention will be described.

The sixth embodiment of the present invention will be described withreference to FIGS. 22 to 27B.

An upper side of FIG. 22 is a plan view illustrating a substrate 1001 ofthe present embodiment. The substrate 1001 includes a plate- orsheet-shaped base 1010, and an electrode 1020 formed on a surface of thebase 1010.

The base 1010 is formed of an insulator or a semiconductor in a plate orsheet shape having a predetermined thickness. Examples of the insulatorand the semiconductor constituting the base 1010 may include silicon,resin, ceramics, and glass. In the present embodiment, a silicon waferis used as the base 1010.

Further, although not shown, a wiring electrically connected to theelectrode 1020 is formed in the base 1010. An aspect of the wiring maybe formed on one or both surfaces in a thickness direction of the base1010 by printing, etching or the like or may be formed to pass throughthe base, like a via. Further, the aspect of the wiring may be athree-dimensional wiring using stacking technology or may be anappropriate combination thereof.

The one surface of the base 1010 is a bonded surface 1010A that isbonded to another substrate. A plurality of rectangular unit regions1011 are provided in the bonded surface 1010A. Further, one electrode1020 having a plurality of electrodes formed with the same layout isformed in each unit region 1011 of the bonded surface 1010A and the sameaspect of wiring is formed.

FIG. 23 is an enlarged schematic diagram illustrating the unit region1011. The electrode 1020 is formed in a substantially rectangular shape,when viewed in a plan view of the substrate 1001, by two-dimensionallyarranging a plurality of fine projecting electrodes (circuit electrodes)on the base 1010. A region around the electrode 1020, includingboundaries 1012 between adjacent unit regions, is a dummy region 1021 inwhich a plurality of dummy electrodes are arranged.

The boundary 1012 becomes a cutting line at the time of singulation,which will be described below, i.e., a so-called scribe line, but is aconceptual line and need not necessarily be formed in a line shape onthe base 1010.

FIG. 24 is an enlarged diagram illustrating a boundary between theelectrode 1020 and the dummy region 1021. A plurality of circuitelectrodes 1020 a formed in the electrode 1020 and dummy electrodes 1021a formed in the dummy region differ only in whether or not theelectrodes are connected to the wirings. Materials and methods of theelectrodes may be the same. The height of the dummy electrode 1021 a isset to be equal to or less than that of the circuit electrode 1020 a.Further, the dummy electrode 1021 a may be connected to portions that donot perform signal transfer, such as a supply voltage and a ground.

The circuit electrodes 1020 a and the dummy electrodes 1021 a are formedof a conductive material, such as a metal. Further, it is desirable forthe circuit electrodes 1020 a and the dummy electrodes 1021 a to beformed of any one of gold, copper, nickel, and an alloy containing atleast one of these metals. Further, any of the electrodes can besuitably formed by plating or the like.

As illustrated in FIG. 24, the circuit electrodes 1020 a of theelectrode 1020 are formed at substantially the same circuit electrodepitch C, although the pitch is slightly changed in some sites dependingon whether or not a semiconductor element is provided in the base, anarrangement of the semiconductor element, or the like.

On the other hand, the dummy electrodes 1021 a form dummy electrode sets1022 in which a predetermined number of dummy electrodes are arranged ata predetermined dummy pitch A1 and a maximum distance between theelectrodes is A2, and the respective dummy electrode sets 1022 areformed to be arranged at a predetermined set pitch B. In the presentembodiment, each dummy electrode set 1022 includes four dummy electrodes1021 a and is arranged so that the four dummy electrodes 1021 a form asquare.

The inventors of the present invention have examined various patternsfor an arrangement aspect when decimating dummy bumps using simulation.There are a case in which another dummy electrode is arranged within apredetermined distance from one dummy electrode and a case in whichanother dummy electrode is not arranged within the predetermineddistance. It has been found that stress applied to the dummy electrodein the latter is several times greater than that in the former.

A mechanism of such a phenomenon is still unclear, but the phenomenonmay be considered to be generally for the following reasons.

When another dummy electrode is not present within a predeterminedradius around a dummy electrode 1021 a as illustrated in FIG. 25A, thedummy electrode 1021 a receives, by itself, a load applied to the othersubstrate 1100. As a result, a substrate 1100 is bent in all directionsaround the dummy electrode 1021 a, and a great stress f1 is applied inall the directions.

On the other hand, there is a case in which another dummy electrode(assigned reference numeral 1021 b for convenience of description inFIG. 25B) is present within a radius 1 from the dummy electrode 1021 a,as illustrated in FIG. 25B. In this case, since the dummy electrode 1021b supports the substrate 1100 in a direction in which the dummyelectrode 1021 b is present around the dummy electrode 1021 a, flexureof the substrate 1100 is reduced and a stress f2 smaller than the stressf1 is applied. Similarly, as the dummy electrode 1021 a is present evenfor the dummy electrode 1021 b, the flexure of the substrate 1100 ispartially reduced and a stress in some directions becomes f2.

As illustrated in FIG. 25C, in the dummy electrode set 1022 of thepresent embodiment, three other dummy electrodes are all arranged withina range of a radius 1 from one dummy electrode. Accordingly, in thelower left dummy electrode, flexure of the other substrate 1100 in arange b around the lower left dummy electrode is reduced by the threeother dummy electrodes and an applied stress is small. For this reason,a relatively greatly bent region of the other substrate region 1100 islimited to a range a, and a total applied stress can be considered to besmall. A radius 1 is slightly changed according to a diameter of thedummy electrode, the number of dummy electrodes constituting the dummyelectrode set, or the like, but may be considered to be a value that isgenerally 3 times the diameter of the dummy electrode.

In the present invention, specific values of the dummy pitch A1, themaximum distance between the dummy electrodes A2, the set pitch B, andthe circuit electrode pitch C can be appropriately set within a rangesatisfying the above conditions. However, it is desirable for the dummypitch A1 to be a value equal to or more than the circuit electrode pitchC and be less than the set pitch B because the number of dummyelectrodes can be efficiently reduced.

Further, when the set pitch B is set to be 3 to 10 times the maximumdistance between the dummy electrodes A2 or 10 to 100 times the dummypitch A1, it is possible to more efficiently reduce the number of dummyelectrodes while reducing the stress. However, since the dummyelectrodes may not play a role in holding the mechanical strength, whichis an original purpose of the dummy electrodes, if the set pitch B isset to be too great, it is desirable to exercise caution by checkingusing an appropriate simulation.

At least two substrates in a combination of the substrates 1001, acombination of the substrate 1001 and a substrate having a semiconductorelement formed therein, or a combination between the substrates 1001having a semiconductor element formed therein are interposed betweenpressurizing plates 1131 and 1132 in a state in which bonded surfaces1010A of the substrates are faced, heated and pressurized by a pressapparatus that is not shown, and integrally bonded by direct waferbonding, as shown in a lower side of FIG. 22. Accordingly, it ispossible to form a semiconductor device by electrically bonding theopposing electrodes.

A known wafer bonding apparatus or the like can be used to position thesubstrate at the time of bonding. Further, prior to bonding, the basesurface and the electrode of each substrate may be cleaned by plasmacleaning, reverse sputtering or the like and the electrodes may bebonded using so-called surface activation.

In the substrate 1001 of the present embodiment, because the dummyelectrodes 1021 a are arranged in the dummy region 1021 in the aspect asdescribed above, it is possible to prevent an excessive stress frombeing applied to the respective dummy electrodes 1021 b and performbonding while reducing the number of dummy electrodes as compared to anequal interval arrangement.

After bonding between the substrates ends, a resin is injected into agap between the substrates to protect the bonded circuit electrodes 1020a. FIG. 26 is a view illustrating an example of a cross section near aboundary in the substrate after a resin 1115 is injected. In thisexample, both of the substrate 1001 and the other substrate 1100 includea semiconductor element 1101 formed by impurity doping or the like, anda three-dimensionally formed wiring 1102 on the base 1010. An electrodeof the substrate 1100 is a flat electrode pad 1103 formed on the wiring1102. A hole reaching the wiring 1102 is formed in the surface oppositeto the bonded surface of the other substrate 1100, and is an externalelectrode extraction unit 1104 for connecting an external to terminalwith the wiring 1102. The external electrode extraction unit 1104 may befilled with a conductive material such as a metal.

If a bonded substrate is cut into unit regions 1011 along boundaries1012 using, for example, a blade 1110 as illustrated in FIG. 27A afterthe substrates are bonded (singulation), a semiconductor device 1120sealed with the resin 1115 is completed, as illustrated in FIG. 27B.

As described above, according to the substrate 1001 of the presentembodiment, the dummy electrodes are arranged in the dummy electroderegion 1021 so that the dummy electrode set 1022 includes apredetermined number of dummy electrodes 1021 a, as described above.Accordingly, it is possible to suitably prevent damage of the electrodesor the base at the time of bonding by suitably suppressing applicationof an excessive stress to the individual dummy electrodes whilesuppressing the number of dummy electrodes to be formed.

Further, since the height of the dummy electrode 1021 a is equal to orless than that of the circuit electrode 1020 a, it is possible tosuppress obstruction of bonding of the circuit electrodes due to thedummy electrodes at the time of bonding, thereby suitably bonding thecircuit electrodes.

While the embodiments of the present invention have been describedabove, the technical scope of the present invention is not limited tothe above embodiment, and combinations of the components may be changed,various changes may be made to each component, and each component may beremoved without departing from the scope and spirit of the presentinvention.

First, in the present invention, a shape of the dummy electrode set, thenumber of dummy electrodes in the dummy electrode set, and the like arenot limited to the above examples and may be appropriately set. Forexample, a triangular dummy electrode set 1022A may be formed of threedummy electrodes 1021 a, as in a variant illustrated in FIG. 28. In thiscase, a stress in a range b1 is reduced in the lower left dummyelectrode 1021 a in FIG. 28. Even with other shapes, a stress reductioneffect is obtained as long as the radius 1 is set to be within 10 timesthe diameter of the dummy electrode as a result of the examinationconducted by the inventors.

Further, the dummy electrode set need not be formed in the entire dummyregion and may be formed only in a partial dummy region. In otherregions, the dummy electrodes may be arranged at equal intervals. Evenwith this, a certain effect can be obtained.

Further, as in a variant illustrated in FIG. 29, the substrate 1001 ofthe present invention may be bonded to a surface opposite to a surfaceof the other substrate 1100A in which a wiring 1102 is formed. In thiscase, a hole reaching the wiring 1102 may be provided in a base 1010 ofthe other substrate 1100A, the hole may be filled with a conductivematerial to form a through electrode 1105, and a circuit electrode 1020a and the through electrode 1105 may be bonded. Meanwhile, a portion ofthe wiring 1102 exposed to an upper surface is directly used as anexternal electrode extraction unit 1104A.

Further, three or more substrates, at least one of which is thesubstrate of the present invention, may be bonded to form asemiconductor device.

Types of the substrate of the present invention and a semiconductordevice formed by bonding the substrate are not particularly limited, buta large number of electrodes need be formed at a narrow pitch, like acase in which a circuit electrode diameter or a circuit electrode pitchis 20 micrometers in a solid-state imaging device having a number ofpixels. Accordingly, there are many merits that can be obtained byapplying the present invention, and it is very suitable to apply thestructure of the present invention.

Further, a computer program product for realizing any combination of therespective components or the respective processes described above isvalid as an aspect of the present invention. The computer programproduct refers to a recording medium, an apparatus, a device, or asystem having program code incorporated therein, such as a recordingmedium having program code recorded thereon (a DVD medium, a hard diskmedium, a memory medium, or the like), a computer having program coderecorded thereon, and an Internet system having program code recordedthereon (e.g., a system including a server and a client terminal). Inthis case, each component or each process described above is mounted oneach module, and program code including the mounted module is recordedin the computer program product.

A program for realizing any combination of the components or theprocesses according to the above-described embodiment is also valid asan aspect of the present invention. The object of the present inventioncan be achieved by recording the program in a computer-readablerecording medium and reading and executing the program recorded in therecording medium using a computer.

Here, the “computer” also includes a homepage providing environment (ora display environment) if a WWW system is used. Also, the“computer-readable recording medium” includes a portable medium such asa flexible disk, a magnetic optical disc, a ROM, or CD-ROM, and astorage device such as a hard disk embedded in a computer. Also, the“computer-readable recording medium” includes a medium that holds aprogram for a predetermined time, such as a volatile memory (RAM) insidea computer system consisting of a server and a client when a program istransmitted via a network such as the Internet or a communication linesuch as telephone line.

Further, the above-described program may be transmitted from a computerin which the program is stored in a storage device or the like to othercomputers via a transmission medium or by transmission waves in thetransmission medium. Here, the “transmission medium” for transmittingthe program refers to a medium having a function of transmittinginformation, such as a network (communication network) such as theInternet or a communication line such as a telephone line. Also, theabove-described program may be a program for realizing some of theabove-described functions. Alternatively, the program may be a programcapable of realizing the above-described functions through a combinationwith a program previously stored in a computer system, i.e., adifferential file (a differential program).

While the preferred embodiments of the present invention have beendescribed above, various alternatives, variations, and equivalents maybe used as each component or each process described above. In theembodiments disclosed in the present disclosure, one part may besubstituted with a plurality of parts or a plurality of parts may besubstituted with one part to execute one or a plurality of functions.Such substitutions fall in a range of the present invention except for acase in which the substitutions do not appropriately act in order toachieve the object of the present invention. Accordingly, the range ofthe present invention is not determined with reference to the abovedescription, but may be determined by claims, including an entire scopeof equivalents. In the claims, the number of each component is one ormore, unless explicitly stated otherwise. It should not be construedthat the claims include a means-plus-function limitation unlessexplicitly described using phrases such as “means for . . . ” in theclaims.

The terminology used in the present disclosure is for the purpose ofdescribing particular embodiments only and is not intended to limit thepresent invention. In this disclosure, the singular forms “a,” “an” and“the” are intended to include the plurality of forms as well, unless thecontext clearly indicates otherwise.

While the preferred embodiments of the present invention have beendescribed, the present invention is not limited to these embodiments.Additions, omissions, substitutions, and other modifications ofcomponents are possible without departing from the scope and spirit ofthe present invention. The present invention is limited by theabove-described description and is limited only by the scope of theappended claims.

What is claimed is:
 1. A solid-state imaging device comprising: a firstsubstrate formed on a first semiconductor wafer; a second substrateformed on a second semiconductor wafer; and a connector electricallyconnects the substrates, wherein the first substrate and the secondsubstrate are bonded via the connector; the first substrate includes aphotoelectric conversion unit; the second substrate includes an outputcircuit that acquires a signal generated by the photoelectric conversionunit via the connector and outputs the signal; and dummy connectors thatsupport the first and second substrates that are bonded with each otherare further arranged in a substrate region in which the connector is notarranged, in a substrate region of at least one of the first substrateand the second substrate.
 2. The solid-state imaging device according toclaim 1, wherein: an arrangement interval of the dummy connectors is thesame as an arrangement interval of the connector.
 3. The solid-stateimaging device according to claim 2, wherein: an arrangement of at leastone of the dummy connectors is omitted.
 4. The solid-state imagingdevice according to claim 3, wherein: the arrangement of the dummyconnectors is omitted to reduce pressure to be applied to the firstsemiconductor wafer and the second semiconductor wafer at the time ofthe bonding.
 5. The solid-state imaging device according to claim 2,wherein: an arrangement position of at least one of the dummy connectorsis shifted from arrangement positions at equal intervals.
 6. Thesolid-state imaging device according to claim 5, wherein: when dicing isperformed after the first semiconductor wafer and the secondsemiconductor wafer are bonded, arrangement position of the dummyconnectors is shifted from arrangement position at equal interval sothat the first semiconductor wafer and the second semiconductor waferare not separated.
 7. The solid-state imaging device according to claim2, comprising: the first substrate includes a plurality of photoelectricconversion elements wherein the photoelectric conversion elements areclassified into one of one or more groups, and a plurality ofphotoelectric conversion elements classified into the same group shareone connector.
 8. The solid-state imaging device according to claim 1,wherein: the arrangement interval of the dummy connector is the same asan arrangement interval of the photoelectric conversion units.
 9. Thesolid-state imaging device according to claim 8, wherein: an arrangementof at least one of the dummy connectors is omitted.
 10. The solid-stateimaging device according to claim 8, wherein: an arrangement position ofat least one of the dummy connectors is shifted from arrangementpositions at equal intervals.
 11. The solid-state imaging deviceaccording to claim 1, wherein: the dummy connectors are arranged toprevent distortion, cracks, and chipping of the first substrate and thesecond substrate.
 12. The solid-state imaging device according to claim1, wherein: an arrangement interval of at least some of the dummyconnectors is greater than the arrangement interval of the photoelectricconversion units.
 13. The solid-state imaging device according to claim1, wherein: the arrangement interval of at least some of the dummyconnectors is greater than the arrangement interval of the connectors.14. The solid-state imaging device according to claim 1, wherein: aplurality of unit circuits are arranged in a peripheral circuit regiondifferent from a region in which the photoelectric conversion units arearranged, and an arrangement position of the dummy connector arranged ona circuit element constituting the unit circuit is common to theplurality of unit circuits.
 15. The solid-state imaging device accordingto claim 1, wherein: a plurality of unit circuits are arranged in aperipheral circuit region different from a region in which thephotoelectric conversion units are arranged, and the dummy connector isarranged to suppress variations in circuit characteristics of theplurality of unit circuits.
 16. The solid-state imaging device accordingto claim 1, wherein: the first substrate includes a peripheral circuit,and the dummy connectors are arranged in a region outside the peripheralcircuit included in the first substrate.
 17. The solid-state imagingdevice according to claim 1, wherein: the second substrate includes aperipheral circuit, and the dummy connectors are arranged in a regionoutside the peripheral circuit included in the second substrate.
 18. Thesolid-state imaging device according to claim 1, wherein: the firstsubstrate and the second substrate include a peripheral circuit, and thedummy connectors are arranged in regions outside the peripheral circuitincluded in the first substrate and outside the peripheral circuitincluded in the second substrate.
 19. The solid-state imaging deviceaccording to claim 1, wherein: the second substrate includes anaccumulation circuit that accumulates a signal acquired via theconnector, and the output circuit outputs the signal accumulated in theaccumulation circuit.
 20. A solid-state imaging device comprising: afirst substrate formed on a first semiconductor wafer; a secondsubstrate formed on a second semiconductor wafer; and a connectorelectrically connects the substrates, wherein the first substrate andthe second substrate are bonded via the connector; the first substrateincludes a photoelectric conversion unit; the second substrate includesan output circuit that acquires a signal generated by the photoelectricconversion unit via the connector and outputs the signal; and dummyconnectors that do not electrically connect the first substrate with thesecond substrate are further arranged in a region in which theconnectors are not arranged, in a substrate region of at least one ofthe first substrate and the second substrate.
 21. An imaging apparatuscomprising: a first substrate formed on a first semiconductor wafer; asecond substrate formed on a second semiconductor wafer; and a connectorelectrically connects the substrates, wherein the first substrate andthe second substrate are bonded via the connector; the first substrateincludes a photoelectric conversion unit; the second substrate includesan output circuit that acquires a signal generated by the photoelectricconversion unit via the connector, and outputs the signal; and dummyconnectors that support the first and second substrates that are bondedwith each other are further arranged in a substrate region in which theconnectors are not arranged, in a substrate region of at least one ofthe first substrate and the second substrate.
 22. A method ofmanufacturing a solid-state imaging device in which a first substrateformed on a first semiconductor wafer and a second substrate formed on asecond semiconductor wafer are bonded via connectors that electricallyconnect the substrates, the method comprising: further arranging dummyconnectors that support the first and second bonded substrates, in asubstrate region in which the connectors are not arranged in a substrateregion of at least one of the first substrate including photoelectricconversion units and the second substrate including an output circuitthat acquires a signal generated by the photoelectric conversion unitvia the connector and outputs the signal.
 23. The solid-state imagingdevice according to claim 1, wherein: the solid-state imaging device isdiced to remove at least some of the dummy connectors.
 24. Thesolid-state imaging device according to claim 1, wherein: a groundwiring is provided in the first substrate, and the ground wiring isconnected to the dummy connector.
 25. The solid-state imaging deviceaccording to claim 1, wherein: a ground wiring is provided in the secondsubstrate, and the ground wiring is connected to the dummy connector.26. The solid-state imaging device according to claim 1, wherein: afirst ground wiring is provided in the first substrate, a second groundwiring is provided in the second substrate, and the first ground wiringand the second ground wiring are connected to the dummy connector. 27.The solid-state imaging device according to claim 23, wherein: heatconduction patterns insulated from the photoelectric conversion unit andconnected to the dummy connectors are provided in the first substrate,and the solid-state imaging device is diced to remove at least some ofthe heat conduction patterns.
 28. The solid-state imaging deviceaccording to claim 23, wherein: heat conduction patterns insulated fromthe output circuit and connected to the dummy connector are provided inthe second substrate, and the solid-state imaging device is diced toremove at least some of the heat conduction patterns.
 29. Thesolid-state imaging device according to claim 23, wherein: a firstwiring insulated from the photoelectric conversion unit and connected tothe dummy connector is provided in the first substrate, a second wiringinsulated from the output circuit and connected to the dummy connectoris provided in the second substrate, and the solid-state imaging deviceis diced to remove at least some of the heat conduction patterns. 30.The method of manufacturing a solid-state imaging device according toclaim 22, comprising: a removal process of performing dicing to removeat least some of the dummy connectors after the connector arrangingprocess.
 31. The method of manufacturing a solid-state imaging deviceaccording to claim 22, wherein: a ground wiring is provided in the firstsubstrate, and the dummy connector is connected to the ground wiring inthe connector arranging process.
 32. A substrate comprising: a basehaving a predetermined thickness; a wiring provided in the base; anelectrode provided in one surface in a thickness direction of the baseand including a plurality of circuit electrodes connected to the wiring;and a dummy region provided in the same surface as the electrode andincluding a plurality of dummy electrodes not connected to the wiring,wherein, in at least a portion of the dummy region, the dummy electrodesare arranged as a dummy electrode set in which a plurality of dummyelectrodes are arranged at a predetermined dummy pitch and a maximumdistance between the dummy electrodes is within a predetermined value.33. The substrate according to claim 32, wherein: a set pitch that is apitch at which the dummy electrode sets are arranged is set to begreater than the dummy pitch.
 34. The substrate according to claim 32,wherein: at least one of a diameter of the circuit electrode and aformation pitch is set to be equal to or less than 20 micrometers. 35.The substrate according to claim 32, wherein: a height of the dummyelectrode is equal to or less than a height of the circuit electrode.36. The substrate according to claim 32, wherein: the set pitch is atleast 10 times the dummy pitch.
 37. The substrate according to claim 32,wherein: the set pitch is at least 3 times the maximum distance betweenthe dummy electrodes.
 38. A semiconductor device formed by bonding atleast two substrates having an electrode formed therein, wherein atleast one of the substrates is the substrate according to claim 32.